SCIENCE  TEXT-BOOK, 


JC-NRLF 


LABORATORY  QUIDE 


IN 


^QENERAL  CHEMISTRY 


BENTON 


D.  C.ffEAfffWCo. 


0 


«  •    ','••' 

________    _„  ...    • 


OFTHK 


UNIVERSITY  OF  CALIFORNIA, 

01  FT  OF 

D  -C  •Beath  &CC  •• 
531    Sanspme^St.  S.T.CV1 

Received         f^^^f' 
Accession  No.  (o  351*?:  '    Clots  No. 


:  AT    I 


LABORATORY    GUIDE 


TWENTY  WEEKS  COURSE 


GENERAL   CHEMISTRY 

CONTAINING 

DETAILED    INSTRUCTIONS   FOR  THE   SUCCESSFUL  PERFORMANCE 
OF   OVER  15O   EXPERIMENTS   IN   GENERAL  INORGANIC 
CHEMISTRY,  AND   USEFUL  TABLES    OF   REF- 
ERENCE  FOR  PUPIL  AND  TEACHER. 


BY 

GEORGE  WILLARD  BENTON,  A.M. 

INSTRUCTOR  IN  CHEMISTRY,  HIGH  SCHOOL,  AND  CHEMIST  FOR  THE  CITY  OF 
INDIANAPOLIS,  IND. 


BOSTON,    U.S.A.: 

D.  C.  HEATH  &  CO.,  PUBLISHERS. 
1893. 


tf 


COPYRIGHT,  1893, 
BY  GEO.  W.  BENTON. 


PREFACE. 


THE  LABORATORY  METHOD  of  teaching  chemistry  is 
thoroughly  established.  Its  superiority  over  the  old 
lecture  methods  has  been  and  is  being  constantly 
demonstrated,  in  the  increased  use  of  text-books  and 
manuals  introducing  chemical  principles  in  simple  form, 
and  in  the  encouragement  of  teachers  who  see  in  the 
Laboratory  the  means  of  high  development  on  approved 
pedagogical  grounds. 

This  method  implies  the  adaptation  of  the  chemical 
course  to  the  capacity  of  the  average  pupil,  not  only  as 
to  apparatus  and  chemicals,  but  in  the  far  more  impor- 
tant matter  of  the  comprehension  of  results  and  the 
development  of  great  principles.  Simplicity  in  the  for- 
mer respect  is  attained  by  the  use  of  materials  whose 
handling  is  least  involved  and  complex.  Success  in 
reaching  results  and  conclusions  lies  in  the  correct  use 
of  the  facts  observed. 

In  the  course,  of  which  these  experiments  are  a  part, 
little  use  is  made  of  the  lecture-room  experiment  and 
only  an  occasional  lecture  is  introduced  as  a  rounding-up 
or  development  step,  following  the  work  in  laboratory 
and  quiz.  The  experiments  themselves  are  simple,  but 
reasonable.  The  book  is  not  a  compilation,  except  in  so 
far  as  all  books  on  the  elements  of  chemistry  are,  of 

3 


4  PREFACE. 

necessity,  compilations.  Again,  it  is  not  a  book  for  the 
teacher,  but  eminently  one  for  the  pupil.  A  good 
teacher  will  be  able  to  furnish  a  bright  pupil  with  any 
amount  of  supplementary  work.  The  teacher's  busi- 
ness in  the  laboratory  is  to  direct,  the  pupil's,  to  do  the 
work.  It  is  believed  that  contact  with  the  thing  itself 
is  essential  for  the  best  development ;  and  it  is  equally 
essential  that  the  sequence  of  fact  and  conclusion  should 
be  attained  by  the  natural  process  of  observation  fol- 
lowed by  discussion.  In  this  belief  the  pupil  is  led  to 
discover,  as  far  as  practicable  by  purely  inductive  pro- 
cesses, the  main  truths  of  the  science,  the  question 
marks  occurring  at  intervals  inviting  to  the  making  of 
many  of  his  own  questions.  Experimentation  is  fol- 
lowed by  quiz  and  discussion,  with  a  sprinkling  of  reci- 
tation from  the  text,  not  omitting  references  to  reliable 
authorities. 

In  this  way  the  pupil  not  only  is  unconsciously  led 
to  adopt  methods  of  logical  thinking,  and  to  come  into 
touch  with  chemical  principles  and  methods  of  deter- 
mining them,  but,  on  the  other  hand,  is  saved  the  dis- 
tasteful task  of  repeating  experiments  which  have  been 
already  seen  and  discussed  in  the  lecture-room.  Such 
repetition  would  necessarily  lack  the  enthusiasm  and 
zest  of  originality ;  the  ingenuity  of  the  pupil  would 
constantly  suffer  from  dearth  of  action,  and  the  whole 
work  become  mechanical.  •  • 

The  use  of  the  note-book  should  be  confined  to  the, 
laboratory,  that  its  statements,  right  or  wrong,  may  be 
free  from  "bookish"  phrases,  and  represent  the  pupil's 
own  work.  The  form  of  the  notes  must  necessarily 
vary  with  the  experiment  and  the  individuality  of  pupil 


PREFA  CE.  5 

and  teacher.  Neat,  concise,  logical,  and  complete  notes 
should  be  insisted  upon  from  the  start,  and  will  soon 
become  the  habit  of  the  careful  student. 

The  favorable  criticisms  of  many  officers  and  teachers 
in  high  Schools  throughout  this  and  other  States,  have 
induced  the  writer  of  these  experiments  to  put  them  in 
permanent  form,  in  the  hope  that  their  use  may  be  ex- 
tended, and  their  influence  upon  elementary  chemical 
education  may  be  marked  and  of  a  high  order. 

It  is  a  pleasure  at  this  time  to  acknowledge  the  assist- 
ance received  from  Mr.  JAMES.  H.  SHEPARD,  author  of 
"  Shepard's  Chemistry,"  from  whose  admirable  book 
much  of  the  material  has  been  adapted,  and  to  which 
reference  is  constantly  made ;  from  Mr.  HUGH  BRYAN, 
Assistant  in  Chemistry,  Indianapolis  High  School,  in 
the  preparation  of  the  manuscript ;  and  Mr.  M.  E. 
CROWELL,  Instructor  in  Physics,  of  the  same  school, 
in  the  criticism  of  manuscript  and  proof.  The  obliga- 
tions of  the  writer  are  also  due  Mr.  E.  F.  HOLDEN,  of 
Melrose,  Mass.;  Mr.  T.  PHOENIX,  New  Britain,  Conn.; 
Mr.  T.  W.  SMITH,  Indianapolis  High  School  No.  2 ;  Mr. 
W.  W.  GRANT,  Providence,  R.  I. ;  Mr.  M.  A.  BRANNON, 
Fort  Wayne  High  School,  and  many  others  who  have 
by  their  criticisms  aided  in  the  presentation  of  the  book 
in  its  present  form. 

G.  W.  B. 

INDIANAPOLIS,  Aug.  10,  1893. 


W7ERSITY 

oar     _, 


FOE    THE    PUPIL. 


1.  This  book  must  not  be  taken  from  the  laboratory 
without   permission.      Statements    written    in   it   must 
represent  your  own  laboratory  work  and  conclusions. 

2.  Write  in  ink  on  the  fly-leaf  of  the  book,  your  name, 
division,  desk,  and  drawer  in  the  laboratory. 

3.  Each  pupil  is  held  responsible  for  the  condition  of 
his  desk  and  apparatus,  and  is  required  to  leave  every- 
thing clean  and  in  good  order. 

4.  Each  pupil   should   have  a  good  pencil,  a  clean 
towel,  old  cloths  for  cleaning  purposes,  an  apron,  a  tin 
or  other  metal  box  with  matches,  and  blank  paper  for 
miscellaneous  use. 

5.  To  clean  a  test-tube,  rinse  it  thoroughly  with  water 
using  a  brush  if  necessary.     If  this  does  not  leave  it 
clean,  use  a  little  cone,  hydrochloric  or  nitric  acid,  or  if 
necessary,  both  at  once,  and  then  rinse  with  plenty  of 
water.     A  tube  will  clean  with  one-tenth  the  time  and 
trouble   if   not    allowed  to  stand  until   dry.     Brushes 
must  not  be  used  with  acids. 

6.  Pupils  should  be,  and  are,  held  responsible  for  all 
unnecessary  or  careless  breakage. 

7.  Glassware  should  be    drained,  not  wiped,  on  the 
inside.     Before  heating,  tubes  and  flasks  should  be  dry 
on  the  outside, 

7 


8  FOR    THE  PUPIL. 

8.  In  heating  test-tubes,  hold  them  in  the  fingers,  using 
the   test-tube  holder  only  when  necessary.      Keep  the 
tube  constantly  moving.     In  the  case  of  solids  which 
may  melt   or   give    up   water,  heat  should  be   applied 
gradually,  to  avoid  breaking. 

9.  Pupils  are  cautioned  not  to  mix  chemicals  or  to 
attempt  experiments  on  their  own  account. 

10.  In  generating  gases,  care  should  be  taken  to  have 
all  joints  tight,  and  corks  in  good  condition. 

11.  In  using  reagent  bottles,  never  lay  the  stoppers 
down.     Hold  them  between  the  first  and  second  fingers 
and  replace  at  once. 

12.  Tubes  to  which  reagents  are  to  be  added,  and  in 
which  liquids  are  to  be  measured,  should  be  held  on  a 
level  with  the  eye. 

13.  In   applying   reagents,  especially   with  work   in 
metals,  add  the  reagent  a  drop  at  a  time.     Remember 
that  more  may  be  added,  but  none  taken  out  of  your 
mixture. 

14.  Nothing  should  be  put  into  reagent  bottles,  not 
even  stirring  rods  or  litmus  paper.     Never  pour  back  a 
reagent  once  removed  from  its  bottle. 

15.  Reagents  found  on  the  side  table  are  for  general 
use,  and  must  not  be  taken  to  individual  desks. 

16.  Only  the  finer-grained  solid  matters  and  liquids 
are  to  be  put  into  the  sink.     Flush  well  with  water, 
especially  when   acids   are   tin-own   out.      Larger  solid 
refuse,  burned  matches,  etc.,  must  be  put  into  the  jars 
provided  for  the  purpose. 

17.  Before   beginning   the  work   of   an   experiment, 


FOR    THE  PUPIL.  9 

read  the  directions  through  carefully,  get  the  necessary 
material  at  hand,  and  then  follow  each  step  intelligently. 
Do  not  attempt  anything  you  do  not  understand.  Ask 
for  an  explanation. 

18.  You  will  have  enough  to  do,  without  attending  to 
the  work  of  your  neighbor. 

19.  In  experimenting,  use  your  own  hands;   in  ob- 
serving, use  your  own  eyes ;  in  reasoning,  use  your  own 
mind  and  common  sense. 

20.  In   making   your   notes,    be    original    and   clear. 
Emphasize   important  facts ;    notice   minor  ones.     Use 
symbols   and   formulae    wherever   possible,  in  case  the 
name  of  a  substance  appears  more  than  once  in  the  same 
experiment. 

21.  Equations  should  be  expressed   in   symbols  and 
formulae,  and  should  not  only  be   completed  but  bal- 
anced.    Constant  use  of  the  table  of  elements  appended 
will  aid  in  equation  work. 

22.  References  to  text-books  should  be  consulted  only 
after  performing  the  experiment. 

23.  Accidents,  as  burns,  etc.,  should  receive  prompt 
attention  from  the  instructor,  to  avoid  annoying  and 
perhaps  serious  consequences. 


CONTENTS. 


SUBJECTS   TREATED   BY   EXPERIMENTS. 

EXPERIMENTS. 

1.  Measurements, 1-2 

2.  Comparison  of  Physical  and  Chemical  Change,  ...  3-6 

3.  Methods  of  Producing  Chemical  Change, 7-9 

4.  Chemical  Processes,       10-  15 

5.  Comparison  of  Elements  and  Compounds,       ....  16-  18 

6.  Mechanical  Mixtures, 19-20 

7.  To  Produce  a  Chemical  Compound   from   a   Mechani- 

cal Mixture, 21 

8.  Oxygen,        22-29 

9.  Phenomena  of  Combustion,        30-  36 

10.  The  Blowpipe  —  Oxidizing  and  Reducing  Flames,  .     .  37-  39 

11.  Kindling  Temperature, 40-  44 

12.  Ozone, 45-46 

13.  Chemistry  of  the  air, 47-48 

14.  Hydrogen, . 49-  55 

15.  Water, 56-58 

16.  Nitrogen, 59-60 

17.  Ammonia, 61-  64 

18.  Neutralizing  an  Acid  with  a  Base, 65 

19.  Nitrogen  and  Oxygen  Compounds, 66-  70 

20.  Nitric   Acid   and   the   Nitrates, 71-78 

21.  Chlorine   and  Chlorides, 79-83 

22.  Bromine  and  Bromides, 84-  88 

23.  Iodine  and  Iodides, 89-94 

24.  Hydrofluoric  Acid, 95 

25.  Carbon, 96 

26.  Carbon  and  Hydrogen, 97-  98 

27.  Destructive  Distillation,  Coal  and  Wood,  Coal  Gas,     .  99-102 

11 


12  CONTENTS. 

EXPERIMENTS. 

28.  Carbon  Monoxide, 103 

29.  Carbon  Dioxide, 104-107 

30.  Carbonates, 108 

31.  Cyanides, 109 

32.  Sulphur,        110-112 

33.  Hydrogen  Sulphide,       113-114 

34.  Sulphur 'Dioxide,       115-116 

35.  Sulphates, 117 

36.  Phosphine, 118 

37.  Tests  for  Common  Acids, 119 

38.  Metals.     Group  I.     Amalgams, 120 

39.  "  "       "      Lead, 121-123 

40.  "  "       "      Silver, 124-126 

41.  "  "       "      Mercury, 127-128 

42.  "  "       "      Separation,    ' 129 

43.  "  "     II.     Arsenic, 130-131 

44.  "  "       "      Tin, 132-133 

45.  "  "      "      Copper,       134-137 

46.  "  "    III.     Iron,       138 

47.  "  "      "      Chromium, 139-140 

48.  "  "       "|^  Aluminum, 141 

49.  "  "       "^Separation    of    Iron,     Chromium, 

and  Aluminum, 142 

50.  "  "       "      Nickel, 143-144 

51.  "  "       "      Cobalt, 145-146 

52.  "  "       'VZinc,  < 147 

53.  "  "    IV.  i,  Barium,  rT 148-149 

54.  "  "       "  ^Strontium,< 150 

55.  Colored  Fire, 151 

56.  Metals.    Group  IV.  ^Calcium,  «~ 152 

57.  "  "       V.  ^Potassium,  .w 153-154 

58.  "  "       "  ^Sodium,  „ 155-156 


THE   APPENDIX. 

1.  Table  of  References  by  Experiments. 

2.  Table  of  Weights  and  Measures. 

3.  Table  of  Principal  Elements. 

4.  List  of  Chemicals  and  Apparatus  for  the  Course. 


HIM 


n    N  0  -  MEASUREMENTS. 


1.  —  Capacity  of  a  Test-Tube.  Draw  in  your 
note-took  two  vertical  parallel  lines,  15  cm  (about  6  in.) 
long,  and  l^cm  (about  £  in.)  apart. 

Connect  the  upper  ends  by  a  straight  line,  the  lower 
by  a  curved  line.  This  figure  represents  the  outline  of 
a  common  test-tube. 

Draw  a  line  10  cm  from  the  bottom,  and  parallel  to  the 
top.  Mark  this  20  cc. 

From  this  data  show  by  measurement  the  part  of 
the  tube  filled  by  10  cc,  5  cc,  and  1  cc  of  a  liquid. 

Would  you  measure  from  the  extreme  bottom  of  the 
curve  in  estimating  capacity?  Give  reason  for  your 
answer. 

Experiment  2.  —  To  approximate  Quantities  of  a  Liquid. 
Compare  a  test-tube  from  your  rack  with  the  diagram 
traced  in  Exp.  1.  Pour  water  into  the  tube,  noting  the 
quantity  required  to  reach  the  lcc,  5CC,  10  cc,  and  20  cc 
marks  in  succession,  measuring  the  depth  and  compar- 
ing with  the  diagram. 

Repeat  the  experiment  until  you  are  able  to  measure 
quantities  with  reasonable  accuracy. 

Do  you  find  all  the  tubes  of  the  same  diameter?  If 
not,  what  allowance  must  be  made  for  these  variations  ? 

14 


16  LABORATORY  GUIDE  IN  CHEMISTRY. 

Note  the  curved  surface  of  the  liquid  in  the  tube. 
It  is  called  the  meniscus.  (?) 

It  is  customary  in  measuring  liquids  to  measure  from 
the  lower  surface  of  the  meniscus. 

PHYSICAL  AND  CHEMICAL  CHANGES. 

Experiment  3.  —  Place  in  a  test-tube  10 cc  of  H2O,  and 
holding  over  the  flame  of  the  Bunsen  burner,  boil  until 
only  5 c  c  remain.  (?) 

Note  the  liquid  condensed  on  the  sides  of  the  tube. 
What  is  it? 

Have  the  changes  just  noted  resulted  from  chemical 
or  physical  action  ? 

Experiment^. — Place  a  crystal  of  iodine  in  a  test- 
tube  and  heat  it  moderately  as  long  as  a  violet  vapor 
arises  from  the  bottom  of  the  tube.  Let  the  tube  cool. 

Examine  the  small  crystals  collected  near  the  top  of 
the  tube.  Compare  with  the  original  crystal.  (?) 

Heat  them  a  little.  (?)  Let  the  tube  cool.  (?) 
Heat  the  crystals  again.  (?) 

Are  you  convinced  that  the  small  crystals  are  of  the 
same  composition  as  the  original  crystal  ? 

Does  this  show  chemical  or  physical  action  ? 

Experiment  5.  —  Examine  a  fragment  of  marble, 
CaCO3.  (?)  Note  taste,  odor,  etc.,  if  any.  (?) 

Place  the  marble  in  a  tube  and  heat  it.     (?) 

When  the  tube  has  cooled,  add  about  5CC  of  H2O, 
and  boil.  (?) 

Now  add  three  or  four  drops  of  concentrated  HC1. 
(?)  Insert  a  lighted  match  into  the  mouth  of  the 
tube.  (?) 


18          LABORATORY  GUIDE  IN  CHEMISTRY. 

Place  in  a  test-tube  5 cc  of  calcium  hydroxide  solu- 
tion, Ca(OH)2,  and  by  means  of  a  delivery  tube  and 
cork  pass  some  of  the  gas  evolved  from  the  marble 
through  the  Ca(OH)2  solution.  (  ?  ) 

Were  the  changes  noted  due  to  chemical  change? 
Give  reason. 

Experiment  6.  —  Place  a  small  piece  of  sheet  copper 
in  a  tube  and  add  about  5  cc  of  dilute  nitric  acid,  HNO3. 
(?)  Note  the  color  of  the  liquid.  (?) 

Take  two  drops  of  the  liquid  011  a  piece  of  glass  and 
warm  gently,  holding  the  glass  in  the  hand  over  the 
flame.  (?) 

Compare  the  product  with  the  original  copper.     (?) 

Indicate  which  process  is  chemical  and  which  is 
physical. 

VARIOUS  WAYS  OF  INDUCING  CHEMICAL  CHANGE. 

Experiment  7.  —  Contact  of  Chemical  Substances.  Mix 
about  .2  gram  each  of  powdered  potassium  chlorate, 
KClOa,  and  sugar  in  an  evaporating  dish. 

Drop  into  the  mixture  4  or  5  drops  of  concentrated 
H2S04.  (?) 

Would  the  first  step  of  Exp.  6  illustrate  the  same 
principle  ? 

Experiment  8.  —  Change  produced  by  Heat.  Hold  a  strip 
of  magnesium  in  your  nippers.  Bring  the  end  into  the 
flame  until  it  becomes  ignited.  (?)  Hold  the  ribbon 
while  burning  over  a  piece  of  paper. 

Examine  the  product.     (?) 

Compare  the  product  with  the  original  magnesium.  (?) 


20  LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  9.  —  Change  produced  by  Solution.  Mix  in 
a  dry  evaporating  dish  a  small  quantity  of  anhydrous 
(?)  ferrous  sulphate,  FeSO4,  and  an  equal  quantity 
of  potassium  ferrocyanide,  K4FeCy6. 

Now  moisten  the  mixture  with  water.     (?) 

Compare  with  the  dry  mixture.     (?) 

Dissolve  in  separate  tubes  a  small  quantity  OA  the 
two  original  powders,  using  about  10 cc  of  water  in 
each.  (?) 

Pour  the  solutions  together.     (?) 

Note  that  it  is  the  contact  of  the  substances  in  water 
which  causes  the  change. 

SOME  PROCESSES  EMPLOYED  IN  CHEMISTRY. 

Experiment  10.  —  Mechanical  Solution.  Place  in  a  tube 
about  .1  gram  of  common  salt,  NaCl.  This  will  fill 
the  curved  part  of  the  tube. 

Add  10 cc  of  H2O.  Examine  carefully  and  note  any 
change. 

Holding  the  tube  in  a  good  light,  shake  it  gently.  (?) 
Finally  shake  vigorously.  (?) 

Is  the  disappearance  of  the  salt  due  to  a  physical  or 
chemical  change  ? 

Problem.  If  lcc  of  H2O  weighs  1  gram,  what  per 
cent  of  NaCl  is  contained  in  the  above  solution  ? 

Experiment  11.  —  Evaporation.  Pour  a  few  drops  of 
the  salt  solution  upon  a  glass  plate ;  hold  over  the  flame 
and  warm  gently  until  the  residue  is  dry.  (?)  Do  not 
let  the  liquid  boil. 

What  has  become  of  the  water  ? 

Examine  the  residue  with  a  magnifying  glass.  (?) 
Note  the  taste.  (?)  Is  it  still  salt  ? 


22  LABORATORY  GUIDE  IN  CHEMISTRY. 

Is  your  answer  to  the  last  question  In  Exp.  10  con- 
firmed ? 

Experiment  12.  —  Chemical  Solution.  Pour  lcc  of  di- 
lute H2SO4  on  a  small  piece  of  zinc  in  a  tube.  (?) 
Heat  gently.  (?)  Compare  Exp.  10. 

After  action  ceases,  evaporate  a  few  drops  of  the  so- 
lution nearly  to  dryness.  (?)  Compare  Exp.  11. 

Examine  the  remaining  substance  with  a  magnifying 
glass.  (?)  Compare  with  the  original  zinc.  (?) 

Distinguish  between  ordinary  or  mechanical  solution 
and  chemical  solution. 

Experiment  13.  —  Precipitation.  To  1 c  c  of  the  salt  solu- 
tion obtained  in  Exp.  10,  add  10 cc  of  H2O. 

Hold  the  tube  in  a  good  light  and  add  about  5  drops 
of  a  solution  of  silver  nitrate,  AgNO3,  a  drop  at  a  time, 
and  note  the  effects.  (?)  The  white  curdy  precipitate 
is  silver  chloride,  AgCl. 

Reaction  :  NaCl  +  AgNO3  =  AgCl  +  NaNO,. 

The  silver  of  the  AgNO3  has  united  with  the  chlorine 
of  the  NaCl  to  form  the  insoluble  solid  AgCl,  thus 
removing  the  chlorine  from  the  salt  solution,  and  the 
silver  from  the  silver  nitrate  solution. 

What  is  the  object  of  precipitation  ?  Would  evapora- 
tion answer  the  same  purpose  ? 

Define  precipitation;  precipitate. 

The  liquid  remaining  after  precipitation  is  called  the 
menstruum. 

Preserve  the  contents  of  the  tube  for  Exp.  14. 

Problem.  What  per  cent  of  salt  was  contained  in  the 
salt  solution  to  which  the  AgNO3  was  added  ? 


24  LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  14.  —  Filtration.  Fold  a  filter,  place  in  a 
funnel,  and  moisten  with  clear  water.  Support  the 
funnel  over  a  clean  tube. 

Shake  the  tube  containing  the  precipitate  prepared  in 
the  last  experiment,  and  holding  a  glass  rod  vertically 
over  the  funnel  and  near  the  filter,  pour  the  contents  of 
the  tube  against  the  rod.  Of  what  advantage  is  the 
rod  ? 

Examine  the  liquid  which  passes  through  the  filter. 
(?)  What  has  been  accomplished  ?  The  clear  liquid 
is  called  the  filtrate.  Would  it  be  possible  to  remove 
all  the  silver  from  a  solution  of  silver  nitrate  by  treat- 
ing it  as  in  Exps.  13  and  14  ?  Give  reasons  for  answer. 

Experiment  15.  —  Decantation.  Treat  5 c  c  of  the  salt 
solution  with  about  5  drops  of  AgNO3  solution  as  be- 
fore. (?)  Compare  Exp.  13. 

Shake  vigorously  and  allow  to  stand  a  few  moments. 
The  precipitate  settles. 

Now  pour  off  the  clear  liquid  leaving  the  precipitate 
in  the  tube.  This  process  is  called  decantation.  Com- 
pare Exp.  14. 

Which  takes  the  less  time  and  which  is  the  more 
accurate  ? 

Now  take  in  a  clean  tube  1 c  c  of  barium  chloride 
solution,  BaCl2 ;  dilute  to  5CC  with  H2O  and  add  two 
drops  of  dil.  H2SO4.  (?)  * 

Shake  vigorously  and  let  stand  as  before.     (?) 

Could  decanting  always  take  the  place  of  filtering  ? 
Why? 


26  LABORATORY  GUIDE  IN  CHEMISTRY. 

COMPARISON  OF  ELEMENTS  AND  COMPOUNDS. 

Experiment  16.  —  The  Element.  Examine  a  piece  of 
platinum  wire.  Hold  the  wire  in  the  non-luminous,  or 
hot  flame.  (?)  Remove  from  the  flame  and  examine. 
Is  the  wire  changed  by  heating? 

Place  another  piece  of  the  wire  in  a  test-tube.  Add 
2ccof  cone.  HNO3.  (?)  Heat  to  the  boiling  point.  (?) 

Wash  the  wire  well  by  filling  the  tube  twice  with 
water  and  pouring  off  again  slowly,  in  order  not  to  wash 
away  the  wire. 

Add  as  before,  2CC  of  cone.  HC1.  (?)  Heat  until 
near  the  boiling  point.  (  HC1  should  not  be  boiled,  as 
it  drives  off  the  acid.)  (?) 

Have  you  succeeded  in  reducing  the  platinum  to 
simpler  substances  ?  Define  an  element. 

Experiment  17.  —  The  Compound.  Take  in  a  clean  dry 
test-tube  a  piece  of  match  stick  about  1  in.  long. 

Heat  gradually  and  evenly,  rolling  the  tube  in  the 
fingers  until  the  stick  ceases  to  undergo  change.  (?) 

Note  the  liquid  produced,  also  the  smoke  and  other 
products.  (?) 

Have  you  succeeded  in  producing  simpler  substances 
out  of  the  pine  stick  ? 

Remove  and  examine  a  piece  of  the  charred"  product. 
(?)  Note  its  weight. 

Place  the  charcoal  thus  prepared  on  a  piece  of  plati- 
num foil,  and  holding  with  your  nippers,  subject  it  to 
the  heat  of  the  Bunsen  flame  until  no  further  change  is 
noted.  (?) 

Compare  results  in  this  experiment  with  the  result  in 
Exp.  16.  (?) 


28  LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  18.  —  The  Compound.  Place  in  an  evaporat- 
ing dish  a  few  grains  of  granulated  sugar,  C12H22On. 

Drop  on  the  sugar  two  or  three  drops  of  strong  sul- 
phuric acid,  H2SO4.  (  ?  )  Warm  gently.  (  ?  ) 

What  is  the  black  substance  produced? 

Note  the  increased  quantity  of  liquid.     What  is  it  ? 

Reaction  : 

Ci2HwOu  +  H2S04  =  12  C  +  11  H20  +  H2SO4. 
Explain  the  equation.     Define  a  compound. 

MECHANICAL  MIXTURES. 

Experiment  19.  —  Mix  intimately  about  equal  parts  of 
fine  iron  filings  and  flowers  of  sulphur.  Compare  the 
mixture  with  the  two  ingredients.  (?) 

Try  to  separate  the  iron  and  sulphur  by  means  of  a 
magnet.  (?) 

Cover  a  small  quantity  of  the  mixture  with  carbon 
disulphide,  CS2,  on  a  watch-glass. 

Drain  the  liquid  onto  a  glass  plate  and  let  it  evapo- 
rate. (?)  Examine  the  remaining  substance.  (?) 

'  Add  to  a  very  small  quantity  of  flowers  of  sulphur 
enough  CS2  to  dissolve  the  sulphur.  Place  the  solu- 
tion on  a  glass  plate  and  allow  to  evaporate.  (?) 

Compare  with  the  previous  product  of  evapora- 
tion. (?) 

Have  you  succeeded  in  separating  the  iron  and  sul- 
phur by  both  processes  ? 

Were  they  physical  or  chemical  processes  ? 

Experiment  20.  —  Mix  equal  parts  of  flowers  of  sul- 
phur, potassium  chlorate,  KC1O3,  and  charcoal.  Corn- 


30          LABORATORY  GUIDE  IN  CHEMISTRY. 

pare  the  mixture  with  the  original  substances.  (?)  Is 
it  possible  to  still  distinguish  the  particles  of  each  ? 

Place  a  filter  in  a  funnel,  put  a  small  quantity  of  the 
mixture  on  the  filter  and  wash  with  about  2CC  of  water. 
Catch  the  filtrate  in  a  clean  tube. 

Pour  three  or  four  drops  upon  a  glass  plate  and 
evaporate  with  a  low  heat.  (?) 

Taste  the  substance.     Taste  some  KC1O3.     (?) 

What  remains  on  the  filter  ? 

Wash  the  residue  on  the  filter  with  about  £cc  of 
CS2.  Collect  the  filtrate  on  a  glass  plate  and  evaporate 
without  heat.  (?)  Compare  Exp.  19.  (?)  What 
remains  on  the  filter  ? 

Have  the  three  substances  been  separated  by  chemi- 
cal or  by  mechanical  means  ? 

Define  a  mechanical  mixture. 


To  PRODUCE  A  CHEMICAL  COMPOUND  FROM  A 
MECHANICAL  MIXTURE. 

Experiment  21.  —  Place  in  a  tin-box  cover  about  a  tea- 
spoonful  of  the  mixture  of  iron  and  sulphur  prepared 
in  Exp.  19. 

Hold  the  cover  in  your  nippers  and  heat  persistently  in 
the  hot  flame  (under  the  hood)  until  a  glow  has  passed 
over  the  mixture.  Some  of  the  sulphur  burns  with  a 
blue  flame  (S  -f-  O2  =  SO2.  Note  the  odor),  while  the 
remainder  combines  with  the  iron. 

Reaction  :  Fe  -f  S  =  FeS.  Some  of  the  iron  may 
remain  uncombined. 

Examine  and  compare  the  cooled  product  with  the 
original  mixture.  (?)  Try  it  with  a  magnet.  (?) 


32          LABORATORY  GUIDE  IN-  CHEMISTRY. 

Moisten  with  one  or  two  drops  of  H2SO4.  (?)  Note 
the  odor. 

When  H2SO4  is  brought  into  contact  with  FeS  the 
odor  of  hydrogen  sulphide  is  noticed.  (?) 

Have  we  evidence  that  the  iron  and  sulphur  com- 
bined? 

PREPARATION  AND  PROPERTIES  OF  OXYGEN. 

Experiment  22.  —  Preparation  from  Mercuric  Oxide,  HgO. 
Take  about  .5  in.  of  mercuric  oxide,  HgO,  in  a  tube. 

Heat  the  tube  gradually  and  evenly,  rolling  it  in  the 
ringers.  Care  must  be  taken  not  to  melt  the  tube,  but 
it  must  be  highly  heated. 

When  hot,  and  continually  held  in  the  flame,  plunge 
into  the  tube,  without  touching  the  contents,  a  glowing 
splinter  of  pine.  (?) 

Have  you  any  evidence  of  chemical  change  taking 
place  ? 

Examine  the  sides  of  the  tube.  (?)  Is  mercury  col- 
lected there  ? 

Reaction  :  HgO  =  Hg  -f-  ^  Explain  the  effect  on 
the  glowing  pine. 

Is  oxygen  solid,  liquid,  or  gaseous  ? 

Experiment  23.  —  Preparation  from  KC103.  Place  in  a 
test-tube  a  few  crystals  of  potassium  chlorate,  KC1O3. 

Heat  carefully.  The  crystals  soon  melt,  and  the 
liquid  appears  to  boil.  In  fact,  oxygen  is  being  evolved. 

Drop  into  the  tube  a  piece  of  match  stick,  and  con- 
tinue to  heat  the  tube  enough  to  keep  up  the  evolution 
of  the  gas.  (?) 

How  does  the  action  compare  with  that  of  Exp.  17  ? 

What  evidence  have  you  that  oxygen  has  been  pre- 
pared ? 


34          LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  24.  —  To  collect  a  Gas  over  Water.  Fill  the 
pneumatic  trough  with  water  until  the  shelf  is  sub- 
merged. Fill  a  wide-mouth  bottle  with  water,  cover 
with  a  glass  plate,  and  holding  the  cover  firmly,  invert 
the  bottle  and  place  on  the  shelf  over  the  opening. 

Why  does  the  water  remain  in  the  bottle  ? 

Hold  the  end  of  a  delivery  tube  beneath  the  opening 
in  the  shelf  and  bfow  gently  through  the  tube.  Bubbles 
of  air  will  rise  through  the  opening  and  gradually  fill 
the  bottle.  Explain  the  change. 

Other  gases  are  collected  over  water  in  the  same  way, 
the  delivery  tube  being  attached  by  means  of  a  cork  to 
the  vessel  in  which  the  gas  is  being  generated. 

Experiment  25.  —  To  collect  Several  Bottles  of  Oxygen. 
Fit  a  test-tube  with  a  good  cork  and  delivery  tube. 
Arrange  four  bottles  to  collect  the  gas  over  water. 

Place  in  the  tube  10 c  c  of  a  mixture  of  four  parts  of 
KC1O3  and  one  part  of  MnO2.  Replace  the  cork  in 
the  tube  and  heat  the  mixture  gently,  passing  the  gas 
evolved  into  the  bottles  in  succession. 

To  avoid  loss,  care  should  be  taken  to  heat  the  mix- 
ture only  sufficiently  to  cause  the  gas  to  come  off  mod- 
erately. 

When  the  bottles  have  beer;  filled,  remove  the  delivery 
tube  from  the  water  at  once,  as  the  water  may  be  drawn 
back  into  the  test-tube  as  it  cools. 

The  gas  thus  collected  is  to  be  used  in  the  four  fol- 
lowing experiments. 

Reaction :  KC1O  3  +  MnO2  =  KC1  +  MnO2  +  ? 

By  reference  to  the  equation  it  will  be  seen  that  the 
MnO2  is  left  after  the  reaction  is  complete. 


36          LABORATORY  GUIDE  IN  CHEMISTRY. 

Compare  the  amount  of  heat  necessary  in  this  experi- 
ment with  that  required  in  Exp.  23.  (?)  Compare  the 
ingredients  used.  (?) 

What  inference  may  be  drawn  concerning  the  influ- 
ence of  the  MnO2.  (?) 

The  MnO2  may  be  recovered  by  washing  well  with 
water  and  filtering.  It  remains  on  the  filter. 

Experiment  26.  —  To  burn  Charcoal  in  Oxygen.  Remove 
a  bottle  of  oxygen  from  the  pneumatic  trough  and  stand 
it  upright  on  the  table,  keeping  the  bottle  covered  with 
the  glass  plate.  The  bottle  should  contain  a  little 
water,  to  prevent  breaking  in  case  the  charcoal  should 
fall. 

Make  a  small  loop  at  the  end  of  a  wire  and  place  in 
it  a  piece  of  charcoal  about  the  size  of  a  pea. 

Heat  in  the  flame  until  lighted,  and  then  plunge  the 
charcoal  into  the  gas.  (?)  Compare  Exp.  23.  (?) 

What  is  the  product  of  the  combustion  ?    C  +  2O  =  ? 

Experiment  27.  —  To  burn  Iron  in  Oxygen.  Wind  a 
piece  of  'fine  iron  wire  into  the  form  of  a  spiral  by  means 
of  a  round  pencil.  Make  a  small  loop  at  the  end  as 
large  as  a  pin-head. 

Holding  the  wire  in  a  pair  of  nippers,  heat  the  loop 
and  coil  until  red  hot,  plunge  while  hot  into  some 
flowers  of  sulphur,  and  then  quickly  into  the  bottle  of 
oxygen  and  replace  the  cover,  as  the  gas  will  otherwise 
escape.  (?)  As  before,  the  bottle  should  contain  some 
water. 

Does  iron  burn  readily  in  air  ?  Is  oxygen  an  active 
supporter  of  combustion? 

Equation :  3Fe  +  4O  =  Fe3O4. 


38          LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  28.  —  To  burn  Phosphorus  in  Oxygen.  Place 
on  the  table  another  bottle  of  oxygen,  containing  a  little 
water,  and  covered. 

Take  a  small  piece  of  dry  phosphorus  in  a  combustion 
spoon.  (Phosphorus  must  never  be  handled  with  the 
fingers.  Use  nippers.  It  is  kept  under  water  to  pre- 
vent contact  with  the  oxygen  of  the  air.) 

Ignite  the  phosphorus  by  holding  the  spoon  in  the 
flame  for  an  instant.  Quickly  plunge  the  spoon  into 
the  bottle  and  replace  the  cover.  (?)  Phosphorus 
pentoxide  is  formed.  Reaction :  2P  +  5O  =  P2O5. 

Let  the  bottle  stand  for  a  few  moments.  (?)  3H2O 
+  P2O5  =  2H3PO4.  H3PO4  is  phosphoric  acid.  Try 
the  liquid  with  litmus  paper.  (?)  What  has  hap- 
pened to  the  white  fumes  ? 

Experiment  29.  —  To  burn  Magnesium  in  Oxygen.  Hold 
a  strip  of  magnesium  ribbon  in  your  nippers.  Ignite 
and  plunge  the  ribbon  into  a  jar  of  oxygen.  (?) 

Compare  the  product  with  the  magnesium.  Are  any 
black  particles  mixed  with  the  white  ? 

Equation :  Mg  +  O  =  ? 

Magnesium  oxide  is  a  white  powder.  Should  there 
be  any  black  particles  ?  Compare  the  burning  of  mag- 
nesium in  air  (Exp.  8)  with  that  in  oxygen. 

PHENOMENA  or  COMBUSTION. 

Experiment  30.  —  Structure  of  a  Flame.  Bring  a  piece 
of  cardboard,  held  horizontally,  against  the  wick  of  a 
burning  candle. 

Quickly  bring  the  card  to  a  vertical  position  against 
the  wick.  The  flame  is  outlined  on  the  card,  and  pre- 


40          LABORATORY  GUIDE  IN  CHEMISTRY. 

sents  a  longitudinal  section.  Remove  the  card  quickly 
to  prevent  burning. 

Now  bring  a  fresh  card  horizontally  down  over  the 
flame,  and  nearly  touching  the  wick.  A  cross  section 
of  the  flame  is  produced. 

Now  examine  the  flame  closely.  Note  the  cup-shaped 
blue  or  colorless  portion  surrounding  the  wick;  the 
cone-shaped  continuation  of  the  colorless  zone  above 
the  wick ;  the  surrounding  envelope  of  luminous  flame 
and  the  very  thin  envelope  of  non-luminous  flame  sur- 
rounding all. 

The  sections  on  the  cardboard  give  only  two  distinct 
zones.  (?) 

Draw  a  diagram  indicating  the  zones  of  no  combus- 
tion, incomplete  and  complete  combustion. 

Experiment  31 Structure  of  Flame  continued.  Hold 

a  pine  splinter  across  the  top  of  the  wick  of  a  lighted 
candle. 

When  the  stick  begins  to  char,  quickly  remove  it  and 
stop  its  burning.  Observe  both  upper  and  under  sur- 
faces of  the  stick.  (?) 

Is  this  result  consistent  with  what  has  already  been 
found? 

Experiment  32.  —  Structure  of  Flame  continued.  Hold 
the  lower  end  of  a  glass  tube  in  the  centre  of  the  lumi- 
nous flame,  the  tube  slanting  upward  at  an  angle  of 
about  45  degrees.  Hold  a  lighted  match  at  the  upper 
end  of  the  tube.  (?) 

What  is  the  condition  of  the  inner  part  of  the  flame  ? 
Why? 


42          LABORATORY  GUIDE  IN   CHEMISTRY. 

Experiment  33.  —  Source  of  the  Light  of  the  Luminous 
Flame.  Hold  a  cold  dry  iron  spoon,  down  in  the  lumi- 
nous flame  for  a  few  seconds,  but  not  long  enough  to  get 
the  spoon  red  hot.  Remove  and  examine  the  spoon.  (?) 

Notice  the  black  smoke  rising  the  instant  the  spoon 
touches  the  flame.  (?) 

Now  open  the  holes  at  the  base  of  the  burner.  (?) 
Hold  the  spoon  with  the  black  deposit  on  it  in  the  non- 
luminous  flame,  and  note  effect.  (?) 

What  was  the  black  substance ?  What  causes  the  light? 

Why  .does  the  light  only  appear  when  the  holes  at 
the  base  are  closed  ?  (?) 

Hold  the  cold  spoon  in  the  flame  of  a  candle  as 
before.  (?)  What  is  the  deposit  ? 

Hold  the  spoon  in  the  non-luminous  flame  of  the 
burner  as  before.  (?)  Is  the  light  of  the  candle  due 
to  the  same  cause  ? 

Carbon  and  hydrogen  are  the  fuels  in  both  cases. 
One  is  solid,  the  other  gaseous.  (?) 

When  they  burn  in  oxygen,  what  are  the  products  ? 
Reactions :  C  +  O2=?;  H2  +  O=?  Both  products 
of  combustion  are  colorless.  This  explains  the  fact  that 
a  flame  burning  quietly  has  a  well-defined  outline  and 
no  visible  products. 

Experiment  34.  —  Air  and  Combustion.  Invert  a  com- 
mon glass  tumbler  over  a  candle  flame,  excluding  the 
outside  air.  (?)  Explain.  Has  oxygen  any  connec- 
tion with  that  action? 

Try  the  same  thing  again,  except  that  this  time  hold 
the  tumbler  so  that  the  candle  may  be  near  its  side,  and 
free  access  of  air  be  allowed.  (?)  Explain. 


44          LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  35.  —  Ventilation  and  Combustion.  Stand  a 
lamp  chimney  down  over  a  lighted  candle  completely 
excluding  air  from  below.  Note  the  effect  on  flame. 

Raise  the  chimney  a  little  from  the  support  and  allow 
free  circulation  of  air.  Any  effect  ?  Explain. 

Still  holding  the  chimney  free  from  the  support,  place 
a  strip  of  glass  over  the  top.  (?)  Explain. 

What  do  you  learn  about  draughts  and  ventilation  in 
this  experiment? 

Experiment  36.  —  Ventilation  and  Combustion  continued. 
Hang  a  strip  of  tin  or  zinc,  about  4  to  6  in.  long,  from 
the  top  of  a  lamp  chimney,  to  partition  the  chimney 
into  two  parts. 

Bring  the  chimney,  thus  prepared,  firmly  down  over 
a  lighted  candle,  excluding  the  air  from  below,  as  be- 
fore. (?)  Bring  a  strip  of  lighted  touch  paper  over 
the  chimney.  (?) 

Why  does  the  candle  continue  to  burn?  How  does 
the  touch  paper  aid  in  explaining  the  action  ? 

THE  BLOWPIPE.  —  OXIDIZING  AND  REDUCING 
FLAMES. 

Experiment  37.  —  The  Oxidizing  Process.  Make  a  small 
loop  at  the  end  of  a  platinum  wire.  Heat  the  wire,  dip 
it  into  borax,  and  heat  with  the  blowpipe  until  a  color- 
less bead  is  formed. 

Touch  the  bead  while  hot  to  a  very  small  particle  of 
manganese  dioxide,  MnO2.  Heat  strongly  for  a  moment 
in  the  oxidizing  flame. 

Hold  the  bead  up  to  the  light,  and  note  the  color 
while  hot,  and  when  cold.  (?) 


46          LABORATORY  GUIDE  IN  CHEMISTRY. 

What  is  meant  by  the  term  oxidizing  ?    Does  oxygen 
come  from  or  go  to  the  bead  in  this  experiment?    How? 
How  is  the  oxidizing  flame  produced  ? 

Experiment  38.  —  The  Reducing  Process.  Heat  the  red- 
colored  bead  produced  in  Exp.  37  persistently  in  the 
reducing  flame  until  the  bead  becomes  clear. 

The  flame  contains  an  excess  of  carbon  and  hydrogen, 
highly  heated.  Both  elements  have  a  strong  affinity  for 
oxygen.  Hence  the  oxidized  bead  heated  in  the  pres- 
ence of  carbon  and  hydrogen  is  caused  to  give  up  its  oxy- 
gen. This  is  called  reduction.  Compare  oxidation.  (?) 

Experiment  39.  —  Dip  a  bead,  while  hot,  into  a  solu- 
tion of  cobalt  nitrate,  Co(NO3)2. 

First  heat  the  bead  in  the  oxidizing  flame.  (?)  Then 
in  the  reducing  flame.  (?)  Compare  the  action  with 
that  observed  in  Exps.  37  and  38.  (?) 

From  the  results  observed,  would  you  think  the  bead 
test  for  a  metal  might  be  relied  upon  ?  Confirm  your 
answer  by  reference  to  your  text-book. 

KINDLING  TEMPERATURE. 

Experiment  40.  —  Varies  with  the  Substance.  Place  on  a 
piece  of  porcelain,  as  far  apart  as  possible,  a  small  piece 
of  phosphorus,  one  of  sulphur,  and  one  of  iron.  The 
substances  must  not  touch. 

Now  place  the  porcelain  on  a  tripod-stand,  and  heat  as 
long  as  changes  are  noted,  taking  care  that  each  sub- 
stance on  the  dish  is  equally  heated.  (?) 

Which  burns  first  ?  Which  last  ?  Does  the  iron  burn  ? 
Why  not  ?  Could  it  be  made  to  burn  ?  How  ? 

Which  has  the  lowest  and  which  the  highest  kindling 
point  ? 


48          LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  41.  —  Effect  of  cooling  a  Flame  below  the  Kind  . 
ling  Point.  Take  a  cold  candle.  Light  a  match  and 
bring  it  slowly  down  over  the  wick  until  the  tip  of  the 
wick  is  surrounded  by  a  flame. 

As  soon  as  it  lights,  remove  the  match  and  note  the 
changes  which  the  candle  and  flame  undergo  until  the 
flame  burns  uniformly  and  steadily. 

A  flame  is  a  burning  gas.  Have  you  evidence  of  a 
gas  being  produced  by  the  flame  ? 

Now  bring  a  piece  of  wire  gauze  slowly  down  over 
the  flame.  Note  the  effect  on  the  flame,  on  the  gauze, 
and  above  the  gauze,  as  the  flame-tip  is  reached.  (?) 

Continue  to  lower  the  gauze  until  it  nearly  touches 
the  wick.  Note  appearances  above  and  below  the  gauze 
as  before.  (?) 

Hold  a  lighted  match  over  the  gauze  and  near  enough 
to  ignite  any  gas  which  may  be  rising  from  the  can- 
dle. (?) 

Will  a  gas  burn  when  cooled  below  the  kindling 
point  ?  Read  the  description  of  the  Davy  safety  lamp. 

Experiment  42.  —  Place  the  Bunsen  burner,  with  holes 
at  the  base  closed,  under  the  tripod  and  about  two  inches 
below  the  centre  of  the  gauze  covering.  Turn  on  the 
gas  and  hold  a  lighted  match  above  the  gauze.  (?) 

Repeat  the  experiment,  but  this  time  hold  the  match 
below  the  gauze.  (?)  Compare  Exp.  41.  (?) 

Under  what  circumstances  would  the  gas  burn  above 
if  lighted  below  only  ? 


50          LABORATORY  GUIDE  IN   CHEMISTRY. 

Experiment  43.  —  Make  a  coil  by  winding  a  piece  of 
iron  wire  around  a  pencil  ten  or  twelve  times. 

Bring  the  coil  vertically  down  into  a  candle  flame,  so 
that  the  wick  may  pass  up  into  the  coil.  (?) 

Repeat  the  experiment,  having  heated  the  coil  red  hot 
in  the  flame  of  the  Bunsen  burner,  and  before  the  coil 
cools.  (?) 

Explain  the  difference  in  action.  Compare  Exps.  41 
and  42.  (?) 

Experiment  44.  —  Ignition  of  Fuels  Affected  by  Size  of 
Particles.  Hold  the  lighted  burner  in  a  horiontal  position 
over  an  evaporating  dish. 

*  Sprinkle  some  fine  iron  filings  over  the  flame.     (?) 
Compare  Exp.  27.     (?) 

Examine  the  filings  which  have  fallen  into  the  dish. 
(?)  Which  would  burn  more  readily,  the  larger  or 
smaller  particles  ? 

Since  temperature  and  quantity  of  heat  are  not  sy- 
nonymous terms,  and  the  same  heat  which  would  raise 
one  particle  10  degrees  would  raise  a  particle  ^  as  large 
100  degrees  (see  Physics),  it  follows  that  a  very  small 
particle  of  iron  falling  through  the  flame  would  reach  a 
very  high  temperature,  while  larger  particles  would  not 
become  even  red  hot.  From  this  it  follows  that  very 
fine  dry  dust  becomes  very  combustible  and  easily  rises 
to  the  point  of  ignition. 

PREPARATION,  PROPERTIES,  AND  TESTS  FOR  OZONE. 

Experiment    45.  —  Preparation    by    Electric    Discharge. 

Turn  the  wheel  of  the  Holtz  machine.     At  all  angles 
and  points  a  silent  discharge  may  be  noted. 


52  LABORATORY  GUIDE  IN   CHEMISTRY. 

Inhale  a  little  air  near  one  of  the  brushes.  (?)  The 
odor  is  that  of  ozone. 

Compare  the  odor  arising  from  a  pie.ce  of  phosphorus 
exposed  to  the  air.  (?) 

The  molecular  formula  of  oxygen  is  O2  ;  that  of  ozone 
is  O3.  Complete  the  equation  3O2  ^=  ?O3. 

Problem.  —  If  a  molecule  of  ozone  occupies  the  same 
space  as  a  molecule  of  oxygen,  how  many  cub.  cent, 
of  ozone  would  be  obtained  from  45 c  c  of  oxygen  ? 

Experiment  46.  —  Preparation  by  the  Reduction  of  Potas- 
sium Permanganate.  Take  in  a  test-tube  about  5 c  c  of  a 
strong  solution  of  potassium  permanganate,  KMnO4. 

Add  a  few  drops  of  cone.  H2SO4.  Odor?  Heat 
gently  to  boiling.  Odor? 

Dip  a  strip  of  bibulous  (?)  paper  into  a  solution  of 
potassium  iodide,  KI,  and  starch.  Hold  over,  but  not 
touching,  the  tube's  mouth.  (?)  In  case  no  immediate 
effect  is  noted,  heat  the  tube  again.  (•?  ) 

Ozone  liberates  the  iodine  from  the  KI,  and  iodine 
when  free  attacks  the  starch,  turning  it  blue.  (?) 

What  reasons  have  you  for  inferring  that  ozone  was 
set  free  ? 

Equations  :  (a.)  6KMnO4  +  9H2SO4  =  ?K2SO4  + 
?MnSO4  +  ?H2O  +  ?O3.  (6.)  6KI  +  O3  =  ?K2O+  ?I. 
The  blue  substance  formed  is  called  "  Iodized  Starch." 

CHEMISTRY  OF  THE  Am. 

Experiment  47. —  It  contains  Moisture.  Calcium  chloride, 
CaCl2,  is  deliquescent.  (?)  Place  a  small  piece  on  a 
dry  plate  and  expose  to  the  air  for  a  few  moments.  (?) 


54          LABORATORY  GUIDE   IN  CHEMISTRY. 

Experiment  48.  —  It  contains  Oxygen,  (a)  Take  a  small 
piece  of  metallic  lead  in  a  porcelain  capsule.  Place  the 
capsule  on  a  stand  over  the  hot  flame.  (?) 

When  the  lead  melts,  stir  it  with  an  iron  wire  until  it 
becomes  a  powder.  (?)  The  substance  formed  is  an 
oxide  of  lead. 

Try  the  same  thing  again,  this  time  using  a  piece  of 
zinc.  (?)  The  product  is  yellow  while  hot,  white 
when  cold.  It  is  zinc  oxide,  ZnO. 

(£>).  Heat  a  piece  of  lead,  as  in  (a),  first  covering 
the  lead  with  a  layer  of  borax.  (?)  The  latter  pre- 
vents the  air  coming  in  contact  with  the  metal. 

Is  the  same  effect  produced  as  when  the  air  reached 
the  metal  ? 

Since  in  forming  the  oxides  the  air  is  made  to  give 
up  oxygen,  might  air  be  deprived  of  oxygen  by  burning 
something  ?  (See  the  preparation  of  nitrogen.) 

PREPARATION  AND  PROPERTIES  OF  HYDROGEN. 

Experiment  49.  —  Preparation  from  Sodium  Amalgam. 
Put  a  piece  of  freshly  prepared  amalgam  in  a  dish  of 
water.  Invert  a  small  test-tube,  filled  with  water,  over 
the  amalgam  and  collect  the  gas.  Complete  the  equa- 
tion Na  +  H2O  =  NaOH  +  ?  What  is  collected  in 
the  tube  ? 

Place  a  finger  over  the  mouth  of  the  tube  and,  hold- 
ing it  mouth  down,  remove  from  the  water  and  plunge 
a  blazing  pine  stick  up  into  the  tube.  (?) 

Does  hydrogen  burn  or  support  combustion  ? 

NaOH  is  a  white  solid,  very  soluble  in  water. 

Evaporate  a  few  drops  of  the   liquid   in   the   dish. 


56          LABORATORY  GUIDE  IN  CHEMISTRY. 

(?)  Touch  the  residue  with  a  strip  of  moistened  red 
litmus  paper.  (?) 

Moisten  a  piece  of  the  paper  with  the  solution  of 
NaOH  found  on  the  table.  (  ?  ) 

NaOH  is  alkaline.  Has  the  water  in  the  dish 
acquired  alkaline  properties? 

Experiment  50.  —  Preparation  from  Zinc  and  Hydrochloric 
Acid.  Arrange  to  collect  two  bottles  of  gas  over  water, 
as  in  Exp.  24.  Place  in  a  4  oz.  generating  bottle 
enough  granulated  zinc  to  cover  the  bottom  of  the 
bottle.  Cover  the  zinc  with  water. 

Add  about  5CC  of  cone.  HC1,  quickly  press  the  cork 
attached  to  the  delivery  tube  into  the  bottle,  and  pro- 
ceed to  collect  the  gas  as  before. 

Joints  in  the  apparatus  must  be  especially  tight  in 
this  experiment,  as  hydrogen  is  very  diffusible. 

As  soon  as  the  gas  is  collected,  wash  the  remaining 
zinc  in  the  generating  bottle,  and  leave  in  your  evap- 
orating dish.  It  may  be  used  again. 

Complete  and  balance  the  equation  Zn  -f-  HC1  — 
ZnCl2  +  ?  Gas  collected  will  be  used  in  the  next  two 
experiments. 

Experiment  51.  —  Physical  and  Chemical  Properties  of 
Hydrogen.  Examine  the  gas  collected  in  Exp.  50. 
Note  color  (?),  odor  (?),  etc. 

Recall  whether  the  bubbles  of  gas  as  they  rose  in 
the  collecting  bottles  in  Exp.  50  appeared  to  grow 
smaller  or  not.  In  case  they  grow  rapidly  smaller  the 
gas  is  quite  soluble.  If  they  do  not  decrease  percepti- 
bly, it  is  comparatively  insoluble.  What  can  you  say 
as  to  the  solubility  of  this  gas  ? 


58'        LABORATORY  GUIDE  IN  CHEMISTRY. 

Now  take  a  blazing  pine  splinter  in  one  hand  ;  remove 
a  bottle  of  the  gas,  mouth  down,  and  pass  the  blazing 
splinter  up  into  the  bottle  of  hydrogen.  (?)  Slowly 
withdraw  the  stick.  (?) 

Did  the  stick  burn  in  the  gas  ?  Did  the  gas  burn  at 
the  mouth  of  the  bottle?  Does  hydrogen  support  com- 
bustion ?  Is  it  combustible  ? 

If  the  hydrogen  burns,  what  compound  is  produced  ? 
H2  +  0=? 

Experiment  52.  —  Dif fusibility  and  Lightness  of  Hydrogen. 
Remove  the  remaining  bottle  of  hydrogen  with  the 
cover  glass,  and  stand  it  up  on  the  table,  mouth  up,  and 
covered. 

Bring  a  second  bottle,  empty  or  filled  with  air  only, 
down  over  the  bottle  of  hydrogen,  mouth  down. 

Remove  the  cover  glass,  arid  hold  the  two  bottles 
firmly  together. 

After  a  half-minute  slip  the  glass  cover  between  the 
bottles  again.  . 

Present  the  mouth  of  the  upper  bottle  to  the 
flame.  (?) 

Now,  remove  the  cover  and  present  the  lower  bottle 
to  the  flame.  (?) 

Which  bottle  gave  evidence  of  the  presence  of  a 
larger  proportion  of  hydrogen  ? 

Show  how  the  lightness  and  diffusibility  of  hydrogen 
would  give  rise  to  the  phenomena  noted. 

Experiment  53.  —  Osmosis.     Performed  by  the  Teacher. 

Take  a  glass  tube  about  18  inches  long  and  1  inch  in 
diameter.  Seal  one  end  with  a  thin  (about  |  inch) 
layer  of  plaster  of  Paris.  Set  it  away  until  dry.  The 
plaster  plug  must  under  no  circumstances  be,  moistened. 


KAPH  MIM   LIBRARY 
CHSM.  BLDG.     U.C 
A3C3S3ion  Ho.. 
Shelf 


60          LABORATORY  GUIDE  IN  CHEMISTRY. 

Fill  the  tube  with  hydrogen  by  the  displacement  of 
air.  (?) 

Place  the  open  end  of  the  tube  in  a  beaker  of  water, 
vertically,  and  allow  to  stand,  noting  the  level  of  the 
water  from  time  to  time.  (?)  Explain  the  rising  and 
falling  of  the  liquid  in  the  tube. 

Experiment  54.  —  Combination  of  Hydrogen  and  Oxygen. 
Performed  by  the  Teacher.  Fill  a  strong  pint  bottle, 
having  a  narrow  mouth,  with  water. 

Replace  two-thirds  of  the  water  with  hydrogen,  and 
the  remaining  one-third  with  oxygen. 

Let  the  bottle  stand  for  a  few  moments  to  insure 
thorough  mixing  of  the  gases. 

Place  the  thumb  over  the  mouth  of  the  bottle  and 
stand  it  down  on  the  table,  tightly  closed. 

Remove  the  thumb  and  quickly  bring  a  lighted  match 
close  to  the  mouth  of  the  bottle.  (?) 

Notice  the  flame  seen  throughout  the  bottle  at  the 
instant  of  the  explosion.  What  is  the  product  of 
the  combination  ?  2H  +  O  =  ?  Explain  the  origin  of 
the  sound. 

Experiment  55.  —  Comparison  of  Coal  Gas  and  Hydrogen. 

Arrange  to  collect  a  bottle  of  gas  over  water. 

Detach  the  burner  from  the  gas-tube.  Put  the  end 
of  the  tube  under  the  mouth  of  the  bottle  of  water  and 
turn  on  the  gas. 

When  the  bottle  is  full,  examine  it.  (?)  Insert  a 
blazing  match  as  in  Exp.  51.  (?) 

How  does  the  action  compare  with  that  of  Exp.  51  ? 
In  what  noticeable  features  are  the  two  gases  differ- 
ent? 


62          LABORATORY   GUIDE  IN  CHEMISTRY 

WATER. 

Experiment  56.  —  Generation  of  Water  by  Ordinary  Com- 
bustion. Hold  a  clean,  dry,  and  cold  glass  tumbler  over 
a  candle  flame. 

Notice  the  bottom  and  sides.  (?)  What  is  collected 
there  ?  What  chemical  action  has  taken  place  ?  What 
physical  action?  Why  should  the  tumbler  be  cold  and 
dry? 

Hold  a  cold,  dry,  glass  plate  for  an  instant  over  the 
hot  flame  of  the  Bunsen  burner.  (?) 

If  air  contains  oxygen  ( see  Exp.  48 )  and  the  fuel 
constituents  of  the  candle  and  gas  are  carbon  and  hydro- 
gen (see  Exp.  33),  would  water  probably  be  in  all 
cases  a  product  of  the  burning  of  a  gas  which  con- 
tained hydrogen?  See  the  equation  in  Exp.  54. 

Experiment  57.  —  Analysis  of  Water  by  Electrolysis.  Per- 
formed by  the  Teacher.  Fill  the  electrolysis  apparatus  with 
water  acidulated  with  H2SO4  ( 1  to  20  ),  and  pass  the 
current  until  enough  gas  has  been  collected  to  examine. 

Note  the  volumes  of  the  gases,  and  particularly  which 
gas  is  in  contact  with  respective  poles  of  the  battery. 
(?)  Remove  and  carefully  test  each  gas  in  succession. 
(?)  Compare  Exp.  54.  (?) 

Experiment  58.  —  Water  of  Crystallization.  Heat  a  crys- 
tal of  copper  sulphate,  CuSO4,  on  an  iron  spoon.  (?) 

When  completely  changed,  and  cold,  drop  a  little 
water  on  the  powder.  (?) 

Put  some  of  the  powder  into  a  test-tube  and  add  lcc 
of  water.  (?) 

Pour  the  contents  of  the  tube  into  an  evaporating  dish 
and  evaporate  the  liquid  slowly  without  boiling.  (?) 


64          LABORATORY  GUIDE  IN   CHEMISTRY. 

Compare  the  product  with  the  copper  sulphate  with 
which  you  started.  (?)  Most  crystals  on  examina- 
tion will  prove  to  contain  more  or  less  water.  See  text 
for  formulae  of  crystalline  substances. 

NITROGEN. 

Experiment  59.  —  Preparation  from  Air.  Float  a  tin 
box-cover  on  water  in  a  pneumatic  trough.  Place  on 
the  float  a  small  piece  of  dry  phosphorus. 

Ignite  the  phosphorus  and  bring  an  inverted  glass 
tumbler  quickly  down  over  the  pan,  enclosing  the  air 
and  burning  phosphorus. 

Another  method.  —  Bend  the  handle  of  a  combustion 
spoon  to  the  shape  of  the  letter  V ;  place  the  phosphorus 
in  the  spoon,  ignite,  and  bring  an  inverted  wide-mouth 
bottle  quickly  down  over  the  spoon,  closing  the  mouth 
of  the  bottle  with  water  as  before. 

In  case  the  former  process  is  used,  it  will  be  well  to 
transfer  the  gas  prepared  from  the  tumbler  to  the  wide- 
mouth  bottle  for  further  examination. 

Why  did  a  few  bubbles  of  air  escape  at  the  outset  of 
the  experiment? 

What  element  in  the  air  combines  with  phosphorus  to 
form  white  fumes  ?  Confirm  your  answer  by  reference 
to  Exp.  28. 

While  the  phosphorus  burns  in  the  enclosed  air,  does 
the  volume  of  the  air  remain  the  same  ?  Estimate  the 
new  volume  as  compared  with  the  old.  Account  for 
the  fact  noted. 

Let  the  bottle  stand  until  the  fumes  settle.  The 
collected  gas  will  be  examined  in  the  next  experiment. 


66          LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  60.  —  Properties.  Remove  the  bottle  of  gas 
and  place  it  upright  upon  the  table,  covered  with  the 
glass  plate.  Note  color,  odor,  if  any,  and  effect  on 
litmus  paper.  Insert  a  blazing  pine  splinter.  (?) 

Pour  the  gas  from  the  bottle.  Does  it  rise  or  fall  ? 
Its  sp.  g.  is  0.97.  Which  should  it  do  ? 

What  gas  has  been  prepared  and  examined  ?  Are  its 
properties  active  or  passive  ? 

Moisten  a  strip  of  blue  litmus  paper  in  the  water  left 
in  the  pan.  (?) 

Balance  the  equation  P2O5  +  H2O  =  H3PO4.  Com- 
pare Exps.  28  and  48. 

THE  COMPOUND  AMMONIA,  NH3. 

Experiment  61.  —  Preparation  from  NH4C1  and  lime,  CaO. 
Place  in  the  palm  of  the  hand,  side  by  side,  but  not 
touching,  about  one  grain  of  dry  lime,  CaO,  and  an 
equal  bulk  of  ammonium  chloride,  NH4C1. 

Note  the  odor,  if  any,  of  each.     (?) 

Mix  the  two  substances  with  a  finger  and  rub  the 
mixture  vigorously  for  a  few  moments.  (?)  Examine 
the  mixture,  —  is  it  moist  ?  Complete  the  equation 
CaO  +  2NH4C1  =  CaCl2  +  ?  4-  ? 

Give  such  properties  of  ammonia  as  you  have  observed. 
Is  it  solid,  liquid,  gaseous,  visible,  invisible,  odorless, 
etc.? 

Experiment  62,  —  Preparation  from  a  Solution  of  an  Am- 
monium Salt,  Place  in  a  test-tube  about  5 c  c  of  a  solu- 
tion of  ammonium  chloride,  NH4C1. 

Add  four  or  five  drops  of  a  solution  of  potassium 
hydroxide,  KOH,  (?)  Heat  geutly.  (?)  Any  odor? 


68  LABORATORY  GUIDE  IN  CHEMISTRY. 

Dip  a  clean  glass  stirring  rod  into  hydrochloric  acid, 
HC1,  and  bring  it  over  the  mouth  of  the  tube.  (?) 

Hold  a  moistened  strip  of  red  litmus  paper  over  the 
tube.  (?) 

Show  by  completing  the  following  equation  that  am- 
monia was  produced:  NH4C1  +  KOH  —  ?  +  ?  +  KC1. 

Other  solutions  of  ammonium  salts  will  yield  ammonia 
in  the  same  way. 

Experiment  63.  —  Preparation  from  Organic  Sources, 
Place  a  piece  of  hoof-clipping  in  a  dry  test-tube.  Heat 
it  carefully  and  gently,  without  burning.  (?)  Any 
odor?  Hold  over  the  tube  a  strip  of  moistened  red 
litmus  paper.  (?)  Is  the  presence  of  ammonia  proved? 

Hair,  finger-nails,  and  many  other  organic  substances 
will  respond  to  the  same  test. 

Experiment  64.  —  Simple  Tests  for  Ammonia  in  Solution. 
Take  about  5CC  of  the  solution  to  be  tested  in  a  test- 
tube.  Add  a  few  drops  of  potassium  hydroxide,  KOH. 
Heat  the  tube  and  contents  gently.  (?)  Any  odor? 
Is  ammonia  present  ?  Why  ? 

If  it  is  present,  was  it  free  or  combined  before  you 
added  the  potassium  hydrate  ?  Give  reason  for  answer. 

Hold  over  the  mouth  of  the  tube  a  strip  of  moistened 
red  litmus  paper,  and  heat  as  before.  (?) 

Does  the  change,  if  any,  confirm  your  previous  con- 
clusion concerning  the  presence  of  ammonia.  Explain. 

Now  hold  over  the  mouth  of  the  tube  while  heating 
a  stirring  rod  moistened  with  hydrochloric  acid,  HC1. 
(?)  Have  you  done  a  similar  thing  before?  Was  the 
product  the  same  both  times  ? 

Are  you  convinced  from  the  results  of  the  three  tests 


70  LABORATORY  GUIDE  IN   CHEMISTRY. 

that  ammonia  is  present  in  the  unknown  solution? 
Which  test  do  you  consider  the  most  delicate  and  con- 
vincing ?  Why  ? 

If  you  were  given  a  solid  instead  of  a  liquid  to  test, 
what  would  you  have  done  first  ? 

NEUTRALIZING  AN  ACID  WITH  A  BASE. 

Experiment  65.  —  Formation  of  a  Salt.  Place  an  evapo- 
rating dish  on  a  tripod-stand.  Pour  in  about  3CC  of 
dilute  nitric  acid,  HNO3. 

Add  ammonia  solution  gradually,  constantly  stirring 
with  a  stirring  rod  until  the  mixture  is  neutral.  Test 
the  neutrality  (?)  with  litmus  paper.  If  necessary,  add 
minute  quantities  of  acid  if  too  alkaline,  or  ammonia  if 
too  acid. 

When  neutral,  evaporate  the  contents  of  the  dish 
gradually.  Do  not  let  the  solution  boil,  as  it  drives  off 
the  ammonia. 

What  is  the  solid  substance  in  the  dish  on  evapora- 
tion ?  Complete  the  equation  NH3  -f-  HNO3  =  ? 

THE  COMPOUNDS  OF  NITROGEN  AND  OXYGEN. 

Experiment  66,  —  The  Preparation  of  the  Monoxide,  N20. 

Arrange  to  collect  two  bottles  of  gas  over  water.  Let 
one  bottle  be  small.  Place  the  apparatus  on  the 
tripod-stand  and  heat  the  water  until  it  is  hot  to  the 
hand,  but  not  necessarily  to  the  boiling  point.  Why? 
While  heating  the  water,  fit  a  test-tube  with  a  sound 
cork  and  glass  delivery  tube. 

Place  in  the  tube  a  few  pieces  of  fused  ammonium 
nitrate,  NH4NO3. 


72  LABORATORY  GUIDE  IN  CHEMISTRY. 

Remove  the  burner  from  beneath  the  pan,  and  heat 
the  contents  of  the  tube  gradually  until  it  melts.  Now 
increase  the  heat  enough  to  make  the  nitrate  boil 
steadily. 

As  soon  as  it  begins  to  boil  place  the  delivery  tube 
under  the  larger  bottle  and  collect  the  gas  evolved,  only 
heating  the  tube  enough  to  keep  the  contents  boiling 
briskly.  Collect  the  small  bottle  of  gas. 

Show  by  the  equation  that  nothing  would  be  left 
in  the  tube  if  heated  sufficiently  long.  NH4NO3  -\- 
heat  —  ?  +  ? 

After  the  bottles  of  gas  have  been  collected,  replace 
the  burner  under  the  pan  to  keep  the  water  hot,  until 
the  gas  has  been  examined  in  the  following  experiment. 

Experiment  67.  —  Properties  of  the  Monoxide.  Stand  the 
small  bottle,  covered,  upright  on  the  table.  Examine. 
(?)  Remove  cover  and  inhale  the  gas.  (?) 

So  far,  what  class  of  properties  has  been  observed, 
physical  or  chemical  ? 

Remove  the  larger  bottle.  Plunge  into  the  gas  a 
glowing  splinter  of  pine.  (?)  Compare  the  action 
with  the  result  of  Exp.  22.  (?) 

How  may  this  gas  be  readily  distinguished  from 
oxygen  ?  Which  is  the  more  active  ? 

Experiment  68.  —  Preparation  of  the  Dioxide,  NO.  Proper- 
ties. Place  in  a  generating  bottle,  fitted  with  a  glass 
delivery  tube,  a  few  copper  clippings.  Arrange  to  col- 
lect one  bottle  of  gas  over  water. 

Cover  the  copper  with  water,  and  then  add  1  or  2  cc 
cone,  nitric  acid,  HNO3.  Collect  the  gas  evolved. 


74          LABORATORY  GUIDE  IN  CHEMISTRY. 

Examine    the   gas   in   the    generator.     (?)     Color? 

Does  the  color   remain?     Explain.     Examine    the    gas 

collected.     (?)     Color?     Explain  what  yon  see.     Bal- 

^ance  the  equation  3  Cu  +  ?  HNO3  =  3  Cu(NO8)a  +  ?  NO 

+  ?H20. 

Remove  the  bottle  of  gas,  keeping  the  mouth  of  the 
bottle  covered.  Hold  it  before  the  window,  for  the  sake 
of  good  light,  and  remove  the  cover.  (?) 

Where  have  the  same  fumes  been  seen  before  ?  Ex- 
plain the  action.  What  is  the  formula  of  the  fumes? 
Balance  the  equation  2NO  +  O2  =  ? 

Experiment  69.  —  Preparation  and  Properties  of  the  Tri- 
oxide,  N203.  Fit  a  test-tube  with  a  cork  and  glass 
delivery  tube. 

Place  in  a  small  bottle  on  the  table  a  weak  solution 
of  potassium  permanganate,  KMnO4. 

Fill  the  curved  part  of  the  test-tube  with  starch  and 
add  an  equal  volume  of  cone,  nitric  acid,  HNO3. 

Heat  the  acid  gradually  and  gently,  avoiding  scorch- 
ing the  starch  and  continually  shaking  the  tube,  until 
the  starch  dissolves.  The  heating  may  have  to  be  con- 
tinued a  moment  longer,  but  is  generally  unneces- 
sary. (?) 

As  soon  as  action  commences,  insert  the  cork  and 
delivery  tube  and  pass  the  gas  through  the  solution  of 
permanganate.  (?) 

Carefully  note  the  odor  of  the  gas.  (?)  Compare 
color  with  the  brown  gas  observed  in  Exp.  68.  (?) 

The  action  on  the  permanganate  solution  is  a  test  for 
the  gas.  Try  the  decolorized  liquid  in  the  bottle,  with 
litmus  paper.  (?) 


76  LABORATORY  GUIDE  IN  CHEMISTRY. 

Nitrous  acid,  HNO2,  is  formed  when  N2O3  reacts  with 
H2O.      Complete  and  balance  the    equation  N2O3  +  ? 


As  soon  as  the  work  of  the  experiment  is  completed 
wash  out  the  test-tube  and  flush  the  basin,  as  the  gas  is 
poisonous. 

Experiment  70. — Preparation  of  the  Tetr oxide,  N02. 
Place  in  a  damaged  test-tube  a  crystal  of  lead  nitrate, 
Pb(NO3)2  and  heat  persistently  in  the  hot  flame.  (?) 

Compare  the  fumes  given  off  with  those  observed  in 
Exp.  68.  (?)  Examine  the  dry  yellow  powder  re- 
maining in  the  tube.  (?)  Is  it  the  same  as  the  sub- 
stance labelled  Litharge,  PbO  ?  Complete  the  equation 
Pb(NO3)2  +  heat  =  ?  +  ?  +  O. 

NITRIC  ACID  AND  THE  NITRATES. 

Experiment  71. —  Preparation  of  Nitric  Acid  from  a  Nitrate. 
Take  about  lcc  of  powdered  potassium  nitrate,  KNO3, 
in  a  test-tube.  Add  about  2CC  of  cone,  sulphuric  acid, 
H2S04. 

Heat  carefully.  Examine  the  vapor  arising  in  the 
tube.  (?)  Note  the  liquid  running  down  the  side  of 
the  tube.  (?) 

Have  you  a  reason  for  thinking  the  vapor  and  liquid 
are  of  the  same  composition?  Bring  a  drop  of  ammonia 
on  a  stirring  rod  over  the  tube.  (?)  A  moistened 
strip  of  blue  litmus  paper.  (?) 

In  case  a  brown  vapor  is  seen,  it  is  caused  by  the 
decomposition  of  the  acid. 

Equation :  2HNO3  +  heat  =  H2O  +  2NO2  +  O. 

Mention  properties  of  nitric  acid  noted  in  this  experi- 
ment :  color,  odor,  normal  condition,  etc.  (?) 


78  LABORATORY  GUIDE  IN  CHEMISTRY. 

Notice  bottles  of  cone,  nitric  acid  which  have  been 
exposed  to  strong  light  and  compare  with  those  unex- 
posed.  (?)  Complete  and  balance  the  equation 
KN03  +  H2S04  =  K2S04  +  ? 

Experiment  72.  —  The  Oxidizing  Power  of  Nitric  Acid. 
Take  2  or  3 c  c  of  cone,  nitric  acid,  HNO3,  in  an  evapo- 
rating dish,  and  warm  it  gently. 

Drop  into  the  acid  a  small  piece  of  freshly  cut  phos- 
phorus. Care  must  be  observed  in  this  experiment  to 
avoid  being  burned  by  the  slight  tendency  to  explode. 
The  phosphorus  should  be  carefully  dried  with  bibulous 
paper  before  using.  (?) 

In  case  white  fumes  are  seen,  give  their  formula. 
Compare  Exp.  28.  (?)  To  account  for  brown  fumes, 
see  Exp.  71. 

If,  in  this  case,  the  oxygen  is  in  the  nascent  (?)  state, 
explain  how  it  differs  from  oxygen  as  examined  in 
Exps.  26-9.  (?) 

Experiment  73.  —  Oxidizing  Power  continued.  Take  some 
powdered  charcoal  in  an  iron  spoon,  and  hold  in  the  'hot 
flame  until  it  commences  to  glow. 

Now  by  the  use  of  a  clean  stirring  rod  drop  some  cone, 
nitric  acid  upon  the  glowing  charcoal .  (?) 

Equation:  5C  +  4HNO3  =  5CO2  +  2H2O  +  4N. 

Does  the  equation  account  for  the  explosive  action? 
Read  something  on  gunpowder  to  confirm  your  answer. 

Would  you  expect  the  result  obtained,  when  reference 
is  made  to  the  action  noted  in  Exp.  72  ? 

Do  you  consider  nitric  acid  a  very  stable  compound  ? 
Give  reasons  for  your  answer. 


80  LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  74. — The  Oxidizing  Power  of  a  Nitrate.  Heat 
charcoal  again,  just  as  in  Exp.  73.  Sprinkle  powdered 
potassium  nitrate,  KNO3,  over  the  glowing  charcoal.  •(  ?  ) 

How  does  the  action  compare  with  that  with  nitric 
acid  ?  Would  you  expect  it  from  an  examination  of  the 
formulae  of  the  two  substances  ? 

Would  common  salt,  Nad,  act  in  the  same  way? 
Explain  your  answer. 

Complete  and  balance  the  equation  5C  +  4KNO3 
=  K2CO3  +  3CO2  -f-  ?  Compare  the  equation  in 
Exp.  73.  (?) 

Note  the  white  substance  remaining  on  the  spoon. 
It  is  potassium  carbonate,  K2CO3.  Try  it  with  moist- 
ened litmus  paper.  '  (?) 

Experiment  75.  —  Dyeing  with  HN03.  Dip  a  piece  of 
white  silk  thread  into  very  dilute  nitric  acid.  Dry  it 
by  holding  over  the  flame.  Examine.  (?) 

What  color  is  produced  when  you  get  nitric  acid  on 
your  hands  ? 

Experiment  76.  —  Nitric  Acid  and  Vegetable  Fibre.  Pre- 
pare a  small  ball  of  common  cotton^  and  one  of  gun- 
cotton,  each  about  .5cm  in  diameter. 

Place  the  common  cotton  in  a  clean  evaporating  dish, 
touch  a  match  to  it,  and  watch  it  burn.  (?)  Any- 
thing left  ? 

Now  treat  the  gun-cotton  in  the  same  way.  (?) 
Any  difference  ?  What  causes  the  difference,  'if  any  ? 

What  element  has  caused  more  rapid  combustion  in 
all  these  experiments  ? 

How  does  gun-cotton  differ  from  common  cotton  ? 


82  LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  77.  —  A  Delicate  Test  for  Nitric  Acid  or  a 
Nitrate.  Dissolve  a  small  crystal  of  ferrous  sulphate, 
FeSO4,  in  about  5CC  of  water. 

Take  in  another  tube  a  drop  of  the  solution  to  be 
tested,  and  add  about  3CC  of  concentrated  sulphuric 
acid,  H2SO4. 

Now  pour,  gradually,  the  ferrous  sulphate  solution 
upon  the  contents  of  the  second  tube,  taking  particular 
care  not  to  let  them  mix.  (?)  Shake  the  tube.  (?) 

The  brown  ring  is  conclusive  except  in  the  presence 
of  a  compound  of  bromine. 

Study  the  reaction :  2KNO3  +  4H2SO4  +  10FeSO4  = 
K2SO4  +  3Fe2(SO4)3  +  4H2O  +  2(FeSO^  NO.  The 
last  substance  composes  the  brown  ring. 

Experiment  78.  —  Another  Test  for  a  Nitrate.  Place  a 
piece  of  copper  in  a  test-tube,  and  pour  over  it  about 
5 c  c  of  the  solution  to  be  tested. 

Now  add,  a  drop  at  a  time,  concentrated  sulphuric 
acid  until  action  is  noted.  Look  down  the  tube.  (?) 
Note  the  odor,  if  any.  (?) 

Compare  color  and  odor  with  color  and  odor  noted  in 
Exps.  68  and  70.  (?)  Study  the  equations  2KNO3 
4H2SO4  +  3Cu  =  K2SO4  +  3CuSO4  +  4H2O  +  2NO; 
and  NO  +  O  =  NO2. 

CHLORINE  AND  CHLOKIDES. 

Experiment  79.  —  Preparation  of  Chlorine  from  Mn02  and 
HC1.  Fill  the  curved  part  of  the  test-tube  with  man- 
ganese dioxide,  MnO2. 

Pour  over  this  about  2CC  of  concentrated  hydro- 
chloric acid,  HC1.  Warm  the  mixture  gently.  (?) 


84  LABORATORY  GUIDE  IN  CHEMISTRY. 

Cautiously  inhale  a  little  of  the  vapor  which  arises. 
(?)  Note  color.  (?) 

Hold  moist  litmus  paper  over  the  mouth  of  the 
tube.  (?) 

Complete  and  balance  the  equation  MnO2  +  HC1 
==MnCla+?+? 

Dry  chlorine  will  not  bleach  dry  litmus  paper.  Com- 
plete the  equation  and  show  that  the  bleaching  is  an 
oxidation  process.  H2O  +  Cl  =  HC1  +  ? 

Experiment  80.  —  Preparation  of  Chlorine  from  KC103 
and  HC1.  Properties.  Fill  the  curved  part  of  the  test- 
tube  with  KC1O3.  Add  lcc  of  HC1.  (?)  Compare 
Exp.  79.  (?) 

Attach  a  cork  and  delivery  tube  to  the  test-tube  and 
let  the  gas  bubble  through  some  clear  water  for  a  mo- 
ment. Examine  the  solution.  Note  color,  odor,  etc. 

Add  a  drop  of  the  solution  to  5 c  c  of  aniline  solution 
in  a  tube.  (?) 

Make  some  marks  with  ordinary  red  ink  on  a  piece  of 
printed  newspaper,  place  in  an  evaporating  dish,  and 
pour  over  it  the  remaining  solution  of  chlorine  in 
water.  (  ?  ) 

Printers'  ink  is  mineral  or  inorganic ;  aniline  red, 
organic.  What  statement  may  be  made  concerning  the 
bleaching  powers  of  chlorine  ? 

Experiment  81.  —  Chlorine  and  Combustion.  Generate 
chlorine  in  a  test-tube  by  the  action  of  hydrochloric  acid 
on  potassium  chlorate.  By  means  of  a  delivery  tube 
pass  the  gas  into  a  small  empty  bottle  placed  upright  on 
the  table  and  nearly  covered  by  a  glass  slip. 

When  the  bottle  is  full  of  gas,  as  indicated  by  the 


86  LABORATORY  GUIDE  IN  CHEMISTRY. 

color,  plunge  a  lighted  match  or  pine  splinter  into  the 
bottle.  (?) 

Hydrogen  has  a  strong  affinity  for  chlorine.  (?) 
Carbon  is  set  free.  Note  the  loss  of  color  after  the 
lighted  stick  has  been  placed  in  the  bottle  of  chlorine. 

Compare  Exp.  22.  (?)  Show  how  they  differ.  Try 
a  strip  of  litmus  paper  in  the  bottle  after  using  the 
splinter.  (?)  Does  chlorine  support  combustion  ? 

Complete  the  equation  H2  +  C12  =  ? 

Does  the  litmus  paper  show  the  presence  of  an  acid  ? 
When  H  burns  in  O,  what  is  the  product  ?  Form  the 
equation. 

Experiment  82.  —  Preparation  of  HC1  from  Common  Salt. 
Take  in  a  test-tube  about  .5  gram  of  anhydrous  sodium 
chloride,  common  salt,  NaCl. 

Add  1 c  c  of  concentrated  sulphuric  acid,  H2SO4.  Heat 
gently.  (?)  Very  cautiously  inhale  a  little  of  the  vapor 
arising  from  the  tube.  (?) 

Compare  the  results  of  Exp.  79.  (?)  Bring  am- 
monia on  a  stirring  rod  over  the  mouth  of  the  tube. 

Complete  the  equation  HC1  +  NH3  =  ?  Hold  a 
strip  of  litmus  paper  over  the  tube.  (?)  Compare 
Exp.  79  again.  (?)  Complete  the  equation  2NaCl 
+  H2S04=  ?  +  ? 

Note  the  white  vapors  coming  from  the  tube  at  the 
outset  of  the  experiment.  (?)  HC1  is  very  soluble 
in  cold  water. 

Experiment  83.  —  Test  for  HC1  or  a  Chloride.  Take  5 c  c 
of  the  solution  to  be  tested  in  a  tube.  Add  a  few  drops 
of  a  solution  of  silver  nitrate,  AgNO3.  (?) 

Divide  the  precipitate  into  two  parts  :  To  the  first  add 
a  few  drops  of  nitric  acid.  (?)  To  second,  ammonia.  (?) 


88  LABORATORY  GUIDE  IN  CHEMISTRY. 

It  is  necessary,  in  all  tests,  to  remember  that  the  color 
of  the  precipitate,  and  its  solubility  or  insolubility  in 
certain  reagents,  are  distinguishing  characteristics. 

The  presence  of  a  chloride  is  proved  by  the  fact  that 
no  other  class  of  substances  will  act  in  the  same  way 
with  the  same  reagents. 

BROMINE  AND  BROMIDES. 

Experiment  84.  —  Preparation  of  Bromine  from  a  Bro- 
mide. Take  in  a  tube,  fitted  with  a  cork  and  glass  de- 
livery tube,  a  crystal  of  potassium  bromide,  KBr ;  cover 
with  manganese  dioxide,  MnO2,  and  add  lcc  of  cone. 
H2S04.  (?) 

Attach  the  delivery  tube  to  the  generating  tube,  and 
put  the  end  into  a  clean  test-tube  held  upright  in  a 
tumbler  of  cold  water.  The  bromine  vapors  condense 
on  the  cold  sides  of  the  tube.  Note  color,  odor,  effect 
on  litmus  paper,  etc.  (?)  It  may  be  necessary  to  heat 
the  mixture  slightly. 

Balance  the  equation  KBr  +  MnO2  +  H2SO4  = 
MnSO4+  HKSO4  +  H2O  +  Br. 

Experiment  85.  —  Test  for  Free  Bromine.  The  Ether 
Test.  Place  in  a  test-tube  about  5CC  of  the  solution  to 
be  tested.  Pour  into  this  about  1 c  c  of  ether.  Shake 
the  tube  and  let  contents  settle.  Keep  the  mouth  of 
the  tube  closed  to  prevent  the  escape  of  the  ether. 

Ether  rises  to  the  surface.  Why  ?  Any  change  in 
the  color  of  the  solution  or  ether  ?  What  and  why? 

From  the  color  of  the  vapor  in  Exp.  84,  what  color 
would  you  expect  for  the  ether  in  this  case  ?  Add  a 
drop  of  potassium  hydroxide,  KOH.  Shake.  (?) 


90  LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  86.  —  Test  for  Free  Bromine,  The  CS2  Test. 
Add  to  the  solution  of  free  bromine  in  a  test-tube  .5 c  c  of 
carbon  disulphide,  CS2 ;  shake  vigorously  and  let  settle. 

The  CS2  does  not  mix  with  water,  but,  being  heavier, 
sinks  to  the  bottom  of  the  tube. 

Note  color  of  the  CS2 ;  also  the  color  of  the  solution 
before  and  after  treatment  with  CS2.  (?)  Compare 
the  ether  test.  (?) 

Experiment  87.  —  Test  for  a  Bromide.  The  Silver  Nitrate 
Test.  Take  about  5 c  c  of  the  solution  to  be  tested  in  a 
tube.  Add  two  or  three  drops  of  a  solution  of  silver 
nitrate,  AgNO3.  (?)  Compare  the  precipitate  with 
that  obtained  in  Exp.  83.  (?)  It  should  be  a  little 
more  yellow.  (?) 

Shake  the  precipitate  well  and  divide  into  three  parts. 
Try  the  solubility  of  the  precipitate  in  nitric  acid.  (?) 
In  ammonia.  (?)  and  in  potassium  cyanide,  KCy.  (?) 

How  does  a  test  for  a  bromide  differ  from  that  for 
a  chloride  ? 

Experiment  88.  —  Test  for  a  Bromide.  The  Chlorine  Test. 
To  5 c  c  of  the  solution  to  be  tested,  add  .5 c  c  of  carbon 
disulphide.  Shake.  (?) 

Add  a  drop  of  chlorine  water.  (?)  Shake.  (?) 
Continue  to  add  the  chlorine  water  by  the  drop,  each 
time  shaking  the  tube.  (?) 

Chlorides  are  more  stable  than  bromides  or  iodides. 

Complete  and  balance  the  equation  KBr  +  Cl  =  KC1 
+  ?  Compare  Exp.  86.  (?) 

An  excess  of  chlorine  water  will  cause  a  disappear- 
ance of  color,  owing  to  the  formation  of  the  compound, 
BrCl3.  Account  for  the  brown  color  produced  on  first 
adding  the  chlorine  water. 


92  LABORATORY  GUIDE  IN  CHEMISTRY. 


IODINE  AND  IODIDES. 

Experiment  89.  —  Preparation  of  Iodine  from  an  Iodide. 

Treat  a  crystal  of  potassium  iodide,  KI,  precisely  as  you 
did  the  bromide  in  Exp.  84,  omitting  the  apparatus 
for  collecting.  Compare  results  with  Exp.  84.  (?) 

Examine  the  crystals  collected  on  the  sides  of  the 
tube.  (?)  Heat  them  gently.  (?)  Compare  Exp.  4. 
(?)  Note  odor  and  weight  of  the  vapor.  Touch  the 
crystals  with  the  finger.  (?) 

Experiment  90.  —  Test  for  Free  Iodine.  Treat  the  solu- 
tion to  be  tested  with  CS2  as  in  Exp.  86.  (?) 

How  may  iodine  be  distinguished  from  bromine  ? 

Add  a  drop  of  the  solution  to  lcc  of  starch  solu- 
tion. (?)  See  Exp.  46.  (?) 

Experiment  91.  —  Some  Brilliant  Iodides.  Take  about 
5CC  of  a  solution  of  mercuric  chloride,  HgCl2  in  one 
tube ;  of  silver  nitrate,  AgNO3,  in  another ;  of  lead 
acetate,  Pb(C2H3O2  )  2,  in  another. 

Add  one  or  two  drops  of  a  solution  of  potassium 
iodide  to  each.  Note  the  color  of  the  precipitate  in 
each.  (?) 

Complete  the  equations  HgCl2  -f-  KI  =  ?  +  ?,  Ag  NO3 
+  KI  =  ?  +  ?,  Pb(C2H302)  2  +  KI  =  ?  +  ?  Name  the 
iodides  formed. 

Experiment  92.  —  Test  for  an  Iodide.  The  Silver  Nitrate 
Test.  To  about  5 c  c  of  the  solution  to  be  tested  add 
one  or  two  drops  of  silver  nitrate.  (?) 

The  precipitate  should  have  the  same  color  and  ap- 


94  LABORATORY  GUIDE  IN  CHEMISTRY. 

pearance  as  the  second  in  Exp.  91.  (?)  Compare 
with  the  test  for  a  bromide,  Exp.  87.  (?) 

Divide  the  precipitate  into  three  parts :  Try  in  turn 
with  nitric  acid,  (?)  Ammonia,  (?)  and  Potassium 
cyanide,  KCy.  (?) 

Compare  the  results  with  those  of  Exp.  87.  (?) 
How  does  the  bromide  test  differ  from  the  iodide  ? 

Experiment  93.  —  Test  for  an  Iodide.  The  Chlorine  Test. 
Treat  the  solution  exactly  as  in  Exp.  88,  testing  for 
bromides.  (?)  Note  difference.  (?) 

The  colorless  compound  of  iodine  <ind  chlorine  has 
the  formula  IC13.  Notice  that  the  bromine  and  iodine 
tests  and,  in  fact,  many  of  their  chemical  characteristics, 
are  similar. 

Experiment  94.  —  Detection  of  Chlorides,  Bromides,  and 
Iodides  in  the  same  Solution.  Preliminary  Treatment. 
Take  about  10 cc  of  a  solution  containing  NaCl,  KBr, 
and  KI.  Add  two  or  three  drops  of  AgNO3  solution 
and  shake  the  tube  vigorously.  (?)  See  Exps.  83,  87, 
and  92. 

Continue  to  add  the  AgNO3  by  the  drop,  until  no 
further  precipitation  occurs.  The  precipitate  consists 
of  AgCl,  AgBr  and  Agl.  Write  the  equations. 

Filter  and  wash  the  precipitate  well  with  hot  water. 
The  last  washings  should  give  no  precipitate  with 
HC1.  (?) 

Second  Step.  —  Separation  of  the  Chlorides  from  the  Pre- 
cipitate. Wash  the  precipitate  into  a  clean  tube  through 
a  hole  in  the  bottom  of  the  filter,  using  the  least  pos- 
sible amount  of  water.  Decant  to  5 c  c 

Add  2  or  3  drops  (not  more)  of  a  solution  of  KBr, 


96  LABORATORY  GUIDE  IN  CHEMISTRY. 

and  boil  for  several  minutes.  The  AgCl,  only,  is 
affected.  Reaction :  AgCl  +  KBr  =  AgBr  +  KCL 

Filter  and  test  the  filtrate  for  a  chloride  by  Exp. 
83.  (?)  The  AgBr  is  insoluble,  the  KC1  is  soluble, 
and  hence  is  found  in  the  nitrate. 

Third  Step.  —  Separate  the  bromides  from  the  iodides 
by  treating  the  precipitate  from  which  the  chlorides 
have  been  removed  with  3  or  4  drops  of  a  solution  of 
KI,  as  in  the  second  step.  * 

This  time  the  reaction  is  AgBr  +  KI  =  Agl  +  KBr. 
The  KBr  is  found  in  the  nitrate  on  filtering,  and  is 
tested  by  Exp.  88.  (?) 

The  iodides  are  identified  by  the  yellow  color  of  the 
remaining  precipitate,  and  its  difficult  solubility  in 
NH4OH. 

Fourth  Step.  —  Another  test  for  the  bromides  and 
iodides  is  applied  directly  to  the  original  solution.  It 
depends  upon  the  difference  in  degree  of  the  chemism 
of  chlorine  for  the  bromides  and  iodides. 

Take  5CC  of  the  original  solution.  Add  2  or  3  drops 
of  CS2.  Now  add  chlorine  water,  a  few  drops  at  a 
time,  shaking  in  order  to  mix,  and  note  the  changes. 
Compare  with  the  chlorine  tests  for  bromides  and 
iodides. 

Note  that  the  success  of  the  test  depends  upon  the 
gradual  addition  of  the  chlorine  water.  Which  are 
more  stable  in  the  presence  of  chlorine,  bromides  or 
iodides  ? 

Experiment  95. — Hydrofluoric  Acid,  HF,  and  Etching 
on  Glass.  (This  experiment  should  be  performed  in  the 
gas  chamber  by  the  instructor.) 

Coat  a  piece  of  glass,  by  dipping  into  melted  paraffin, 


98  LABORATORY  GUIDE  IN  CHEMISTRY. 

and  standing  it  on  edge  to  cool.  The  coat  should  be 
thin  and  smooth. 

Trace  with  a  pin  or  needle  the  desired  figure,  cutting 
through  the  paraffin  to  the  glass.  It  is  now  ready  for 
treatment  with  the  acid. 

Place  in  a  lead  dish  some  powdered  CaF2,  fluor- 
spar. Pour  over  it  about  5CC  of  cone.  H2SO4,  and  sus- 
pend the  glass,  face  down,  over  the  dish,  and  as  near  as 
possible  to  it. 

After  the  action  ceases,  warm  the  glass  over  the 
flame,  and  with  a  dry  cloth  wipe  off  the  melted  paraffin. 

The  design  will  be  found  etched  into  the  glass. 
Equations  :  CaF2  +  H2SO4  =  CaSO4  +  ?  and  SiO2 
+  HF  =  SiF4  +  ?  Complete  and  balance. 

CAKBON  AND  CAKBON  COMPOUNDS. 

Experiment  96.  —  Some  Properties  of  Charcoal.  Arrange 
a  filter  paper  in  a  funnel.  Place  on  it  a  small  spoonful 
of  powdered  charcoal.  Pour  on  the  charcoal  about 
10 c  c  of  a  solution  of  red  aniline,  and  catch  the  filtrate 
in  a  clean  tube.  (?) 

As  soon  as  the  solution  has  passed  through,  pour 
on  the  same  or  a  fresh  portion  (the  first  will  do)  about 
5 c  c  of  a  solution  of  potassium  bichromate,  K2Cr2O7, 
and  catch  the  filtrate  in  a  clean  tube.  (?)  The  first 
is  an  organic  color;  the  second,  inorganic.  (?) 

Experiment  97.  —  Hydrocarbons.  Methane  or  Marsh  Gas, 
CH4.  Fit  a  test-tube  with  a  cork,  and  a  delivery  tube 
fitted  with  a  jet.  Place  in  the  tube  about  5 c  c  of  a  mix- 
ture of  2  pts.  of  sodium  acetate,  NaC2H3O2 ;  8  pts.  of 
sodium  hydroxide,  NaOH ;  and  2  pts.  of  calcium  oxide, 
CaO. 


100         LABORATORY  GUIDE  IN  CHEMISTRY. 

Heat  the  tube  and  contents  carefully,  but  strongly 
and  persistently,  bringing  the  jet  near  the  flame  to 
ignite  the  gas  which  is  evolved.  Note  the  odor  of  gas 
(?)  and  flame.  (?) 

In  this  reaction  is  the  calcium  oxide  changed? 
Compare  with  the  action  of  manganese  dioxide  in  Exp. 
25.  (?)  Complete  the  equation  NaC2H3O2  +  NaOH 
==  Na2C03  +  ? 

Experiment  98. — Hydrocarbons.  Ethylene  or  Olefiant 
Gas,  C2H4.  Fit  a  test-tube  as  in  Exp.  97.  Place  in  it 
about  3 c  c  of  alcohol  and  2 c  c  of  cone,  sulphuric  acid. 

Heat  the  tube  and  contents  carefully,  bringing  the 
jet  near  the  flame  as  before.  Compare  the  flame  with 
that  of  Exp.  97.  Complete  the  equation  C2H6O  =  ? 

+? 

The  acid  is  not  decomposed.  It  is  hygroscopic  (?) 
and  extracts  water  from  the  alcohol.  Compare  Exp.  18. 

From  an  inspection  of  the  formulae  CH4  and  C2H4, 
would  you  expect  the  difference  in  the  flames  of  marsh 
and  olefiant  gases  ?  Explain. 

Experiment  99.  —  Destructive  Distillation  of  Coal.  Coal 
Gas.  Place  in  a  test-tube,  fitted  with  a  delivery  tube  and 
jet,  a  few  pieces  of  coarsely  powdered  bituminous  coal. 

Strongly  heat  the  tube  and  contents,  noting  changes 
which  take  place.  (?)  Care  must  be  taken  to  hold 
the  tube  in  a  horizontal  position,  to  prevent  any  moist- 
ure, which  may  condense  on  the  cooler  parts,  from 
running  down  into  the  hotter  part  and  breaking  the 
tube. 

Bring  the  jet  near  the  flame,  as  in  Exps.  97  and  98.- 
(?)  Collect  a  small  bottle  of  the  gas  and  test,  as  in 
Exps.  51  and  55.  (?) 


102         LABORATORY  GUIDE  IK  CHEMISTRY. 

Experiment  100.  —  Destructive  Distillation  of  Wood. 
Wood  Gas.  Treat  a  few  thoroughly  dried  pine  shavings 
in  the  same  way  that  you  did  the  coal  in  Exp.  99,  taking 
the  .same  precautions,  and  noting  the  same  points.  (?) 

Experiment  101.  —  Detection  of  Ammonia,  NH3,  and  Hy- 
drogen Sulphide,  H2S,  in  Coal  Gas.  Place  on  the  top  of 
the  burner  under  a  hood  or  in  a  strong  draught,  a  strip 
of  moistened  red  litmus  paper  and  a  strip  of  bibulous 
paper  moistened  in  lead  acetate  solution.  Close  the 
holes  at  the  base  of  the  burner,  and  turn  on  the  gas.  A 
current  of  gas  will  flow  out  against  the  papers.  (?) 
The  ammonia,  if  present,  will  change  the  litmus.  (?) 
The  hydrogen  sulphide  will  change  the  lead  acetate  to 
the  sulphide  which  is  black.  (?) 

Experiment  102.  —  Detection  of  Carbon  Dioxide,  C02,  in 
Coal  Gas.  Place  a  small  bottle  on  the  table,  add  10 cc  of 
a  solution  of  calcium  hydrate,  Ca(  OH  )2  and  fill  with 
distilled  water. 

Remove  the  connecting  tube  from  the  gas  burner. 
Insert  a  short  glass  tube  and  pass  the  gas  slowly  through 
the  solution  in  the  bottle. 

If  carbon  dioxide  is  present  the  liquid  becomes  milky, 
calcium  carbonate  being  formed. 

Equation:    Ca(OH)2  +  CO2  =  CaCO3  +  H2O.     (?) 

Experiment  103.  —  Carbon  Monoxide,  CO.  Preparation  and 
Properties.  Place  in  a  test-tube  fitted  with  a  cork  and 
delivery  tube  with  jet,  a  few  pieces  of  coarsely  pow- 
dered potassium  ferrocyanide,  K4FeCy6  with  about 
5CC  of  cone,  sulphuric  acid. 

Heat  the  tube  carefully,  and  note  the  odor,  color,  etc. 
of  the  gas  which  escapes.  Bring  the  jet  near  the  flame. 
(?)  Note -the  color,  odor,  and  reaction  of  the  products 
of  the  flame. 


104         LABORATORY  GUIDE  IN  CHEMISTRY. 

Does  the  gas  evolved  change  blue  litmus  paper? 
Does  the  product  of  the  flame  change  the  paper  ?  Com- 
plete the  equation  K4FeC6N6  +  6H2SO4  +  6H2O  = 
K2S04  +  FeS04  +  (  NH4  )2SO4  +  ? 

Experiment  104.  —  Carbon  Dioxide,  C0.2.  Preparation  from 
CaC03  and  HC1.  Fit  a  generating  bottle  with  a  delivery 
tube,  and  arrange  to  collect  four  bottles  of  gas  over 
water. 

Place  in  the  generator  a  few  pieces  of  marble,  calcium 
carbonate,  CaCO3  ;  cover  with  water,  and  add  enough 
cone,  hydrochloric  acid,  HC1,  to  cause  a  rapid  evolution 
of  gas,  which  proceed  to  collect.  Note  color  and  odor 
ofC02.  (?) 

When  the  gas  has  been  collected,  wash  and  save  the 
remaining  marble.  Complete  the  equation  CaCO3  + 
2  HC1  =  CaCl2  +?  +  ?  The  gas  will  be  used  in  Exp. 
105. 

Experiment  105.  —  Carbon  Dioxide,  C02.  Some  Properties. 
(«)  Place  a  bottle  of  CO2  on  the  table,  covered. 
Light  a  pine  splinter,  and  introduce  into  the  bottle.  (?) 

Repeat  the  experiment,  keeping  the  bottle  covered 
when  possible.  (?) 

(  b  )  Take  a  fresh  bottle  of  CO2,  as  in  #,  hold  a  strip 
of  magnesium  ribbon  with  nippers,  ignite  and  introduce 
as  before.  (?*)  Compare  the  action.  (?)  Does  CO2 
support  combustion  ?  Account  for  the  presence  of 
black  particles  found.  (?)  Compare  Exp.  29.  (?) 
Complete  the  equation  CO2  +  2Mg  =  MgO  +  ? 

(<?)  Place  a  small  candle  upright  in  a  common 
tumbler,  near  the  side.  Partly  close  the  opening  with 
the  hand,  and  pour  over  the  flame  the  contents  of  a 
bottle  of  carbon  dioxide  gas.  (?)  Is  CO2  a  heavy 
gas  ?  Why  ? 


106         LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  106.  —  Carbon  Dioxide,  C02,  continued.  Pour 
into  a  bottle  of  carbon  dioxide  about  5 c  c  of  calcium 
hydroxide,  Ca(OH  )2.  Cover  quickly  and  shake  vig- 
orously, noting  appearance  from  time  to  time.  (?) 
Complete  the  equation  :  Ca(  OH  )2  +  CO2  =  ?  +  ? 

Calcium  carbonate  is  soluble  in  an  excess  of  carbon 
dioxide.  Does  that  explain  the  changes  noted  during 
the  shaking  ?  Try  the  solution  in  the  bottle  with  litmus 
paper.  (?)  Moisten  litmus  paper  with  Ca(OH)2.  (?) 

Experiment  107.  —  Carbon  Dioxide,  C02,  exhaled  from  the 
Lungs.  Place  about  10  cc  of  a  clear  solution  of  calcium 
hydroxide  in  a  test-tube.  By  means  of  a  glass  tube 
exhale  air  from  the  lungs  so  that  it  shall  bubble  up 
through  the  liquid.  (?) 

Compare  with  Exp.  106.  (?)  Is  carbon  dioxide 
exhaled  from  the  lungs  ?  Explain  your  answer. 

Experiment  108.  — Test  for  Carbonates.  All  carbonates 
effervesce  (?)  when  treated  with  strong  acids,  such  as 
hydrochloric  and  sulphuric  acids. 

Touch  specimens  of  carbonates  with  a  glass  rod  mois- 
tened with  one  of  these  acids.  (?)  What  is  the  gas 
evolved?  Compare  Exp.  5.  (?) 

State  the  difference  between  common  limestone  and 
marble. 

Experiment  109.  —  Cyanides.  Carbon  and  Nitrogen.  Test 
for  a  Cyanide.  Take  about  5CC  of  the  solution  in  a  test- 
tube.  Add  about  two  drops  of  potassium  hydroxide, 
KOH ;  then  about  three  drops  of  a  solution  of  ferrous 
sulphate,  FeSO4.  Shake  the  tube,  and  acidulate  (?) 
with  hydrochloric  acid.  (?) 

Prussian  blue  is  formed  if  a  cyanide  is  present.     (?) 


108         LABORATORY  GUIDE  IN  CHEMISTRY. 


SULPHUR  AND  SULPHUR  COMPOUNDS. 

Experiment  110.  —  Amorphous  or  Plastic  Sulphur.  Take 
a  spoon  half  full  of  flowers  of  sulphur.  Hold  in  the 
hot  flame  and  notice  that  it  first  melts  to  a  clear  liquid, 
then  turns  dark,  thickens,  and  requires  more  heat  to 
again  melt  it. 

Heat  strongly  and  quickly  until  the  sulphur  boils 
vigorously,  and  is  thin  enough  to  run.  When  suffi- 
ciently heated,  quickly  pour  the  molten  sulphur  into  a 
dish  of  cold  water.  (?) 

Examine  the  product.  What  does  it  resemble?  Is 
it  still  sulphur  ? 

Why  is  it  called  plastic  ?  Lay  the  product  away  and 
examine  to-morrow.  (?)  This  experiment  should  be 
performed  under  the  hood. 

Experiment  111.  —  Sulphur  Crystals  deposited  on  Cooling. 

Heat  common  sulphur  in  a  tube  until  it  boils  freely 
and  pours  easily.  Now  move  so  that  the  inside  surface 
of  the  tube  is  coated  with  the  molten  sulphur  and  let 
it  drain  down. 

As  the  cooling  progresses,  crystals  of  great  variety  of 
form  accumulate  on  the  sides  of  the  tube. 

Examine  the  sublimate  collected  about  the  mouth  of 
the  tube.  (?)  Compare  with  flowers  of  sulphur.  (?) 
Examine  some  of  the  yellow  powder  under  the  micro- 
scope. (?)  Is  it  sulphur  ? 

Experiment  112.  —  Sulphur  Crystals  deposited  from  CS2 
Solution.  Place  on  a  watch-glass  some  flowers  of  sul- 
phur. Pour  upon  the  sulphur  just  enough  carbon  di- 
sulphide  to  dissolve  it.  Let  the  watch-glass  stand  until 


110         LABORATORY  GUIDE  IN  CHEMISTRY. 

the  liquid  has  evaporated.     (?)     Examine  with   the 
microscope. 

Draw  in  your  note-book  the  outline  of  one  of  the 
crystals.  Are  the  crystals  transparent? 

Experiment  113. — Hydrogen  Sulphide,  H2S.  Prepara- 
tion and  Properties.  Fit  a  test-tube  with  a  good  cork 
and  delivery  tube  with  jet.  Put  in  the  tube  three  or  four 
pieces  of  ferrous  sulphide,  FeS,  and  cover  well  with  water. 

Add  cone,  sulphuric  acid  cautiously  until  evolution 
of  gas  takes  place  freely.  Odor?  Color?  Avoid 
inhaling  much  of  the  gas,  as  it  is  poisonous. 

Bring  the  jet  near  the  flame.  (?)  Color  of  flame  ? 
Note  the  odor  arising  from  flame  ?  Complete  the  equa- 
tion H2S  +  3O  =  ?  +  ?  State  the  cause  of  the  odor  of 
the  products  of  the  flame. 

Complete  the  equation  FeS  +  H2SO4  =  ?  +  ?  Try 
the  gas  with  litmus  paper.  (?) 

Experiment  114.  — Test  for  a  Sulphide  in  Solid  State. 
Treat  a  small  quantity  of  the  powdered  substance, 
on  charcoal  with  sodium  carbonate,  before  the  blow- 
pipe. 

Now  place  the  fused  (?)  substance  on  a  bright  silver 
or  copper  coin,  and  moisten  with  a  drop  of  water.  .  If  a 
sulphide  is  present  a  black  spot  appears.  (?) 

Wash  the  coin  with  water,  and  if  the  black  spot  is 
persistent,  drop  upon  it  a  small  quantity  of  a  solution  of 
potassium  cyanide.  (?) 

The  explanation  of  the  reaction  is  that  the  sulphide 
is  changed  to  sodium  sulphide,  Na2S,  which,  moistened 
in  presence  of  silver  or  copper,  forms  silver  or  copper 
sulphide,  which  is  soluble  in  KCy. 


112        LABORATORY  GUIDE.  IN  CHEMISTRY. 

Experiment  115.  —  Sulphur  Dioxide,  S02.  Preparation 
and  Properties.  Place  in  a  test-tube  fitted  with  a  deliv- 
ery tube  a  few  copper  clippings.  Add  about  5CC  of 
cone,  sulphuric  acid.  Heat  until  a  gas  is  evolved. 

Pass  the  gas  into  a  test-tube  containing  about  10 c  c  of 
water.  Save  the  solution.  Note  properties  of  the  gas, 
as  color,  odor,  etc.  As  the  gas  dissolves,  the  bubbles 
become  smaller.  See  Exp.  51. 

Try  the  solution  with  litmus  paper.  (?)  Complete 
the  equation  SO2  +  H2O  —  ?  Compare  the  odor  of 
the  gas  with  that  noticed  in  Exps.  21,  40,  and  110. 
(  ?  )  Complete  the  equation  Cu  +  2  H2SO4  =  CuSO4 
+  ?+? 

Account  for  the  color  of  the  solution  in  the  genera- 
ting tube.  (?)  See  Exp.  58. 

Experiment  116.  —  Sulphur  Dioxide,  S02.  Bleaching  Pro- 
cess. Moisten  the  petal  of  a  rose  or  any  colored  flower 
with  the  solution  of  sulphur  dioxide  obtained  in  Exp. 
115.  (  ?  )  Compare  with  Exp.  79.  (?) 

Now  place  the  petal  in  a  weak  solution  of  sulphuric 
acid  for  a  moment ;  wash,  dry,  and  warm.  (?) 

Show  by  comparison  of  equations  that  chlorine 
bleaches  by  oxidation,  while  sulphur  dioxide  bleaches 
by  reduction : 

Equations  :  C12  +  H2O  =  .HC1  +  ?  and  H2SO3 
+  H20  =  H2S04  +  ? 

Experiment  117.  —  Test  for  a  Sulphate  in  Solution.  Take 
in  a  tube  about  5CC  of  the  solution.  Drop  into  it 
barium  chloride,  BaCl2.  (?)  Complete  the  equation 
H2S04  +  BaCl2  =  ?  +  ? 


114        LABORATORY  GUIDE  IN  CHEMISTRY. 

Try  the  white  precipitate  obtained,  with  nitric,  hydro- 
chloric, and  acetic  acids.  (?) 

Most  sulphates  are  soluble  in  water.  Barium  sulphate 
is  insoluble  in  water,  and  in  acids ;  hence  the  test. 

Experiment    118.  —  Hydrogen  Phosphide,   or   Phosphine. 

This  experiment  should  be  performed  in  the  gas  cham- 
ber by  the  teacher,  as  the  fumes  are  very  poisonous. 

Fit  a  200 c  c  Florence  flask  with  a  cork  and  glass 
delivery  tube.  Place  the  flask  on  a  sand-bath  and  pass 
the  end  of  the  QMiv'e^  tube  beneath  the  surface  of 

water  in  a  dish. 

i>  •          i  «•  *  . 

Pour  into  the  flask  enough  of  a  strong  solution  of 
KOH  (about  1  to  5),  to  cover  the  bottom  of  the  flask 
to  the  depth  of  about  £  inch. 

Drop  into  the  KOH  solution  three  pieces  of  freshly 
cut  phosphorus,  about  the  size  of  a  grain  of  corn. 

Now  add  about  .5 c  c  of  ether ;  attach  the  cork  and 
delivery  tube,  taking  care  that  the  end  dips  below  the 
surface  of  the  water  in  the  dish. 

Heat  the  sand-bath  gradually  until  the  contents  of  the 
flask  boil  briskly.  The  ether  is  vaporized,  and  drives 
out  the  air  from  flask  and  delivery  tube ;  the  hydrogen 
phosphide  which  is  produced  by  the  combined  action  of 
phosphorus,  KOH  and  H2O  only  coming  in  contact  with 
air  upon  bubbling  up  out  of  the  water  in  the  dish.  (?) 

To  stop  the  action  safely,  first  remove  the  cork  and 
delivery  tube  from  the  flask,  then  remove  the  flask  from 
the  sand-bath. 

Complete  the  equation  4P  -f  3KOH  -f  ?  — 

3KH2PO2  +  ? 


Of  THK 


UlU  KAPH   MIM    LI 

CHSM.  3LD7.     U.  C 
A^c^ss  ion   No  „ 
Shelf   Mo 


116         LABORATORY  GUIDE  IN  CHEMISTRY. 

'  Experiment  119.  —  Tests  for  Common  Acids.  Examine 
four  liquids  and  four  solids  each  containing  one  acid, 
either  as  free  acid,  acid  or  normal  salt,  using  the  follow- 
ing table : 

A.  —  IT  is  A  LIQUID  AND  NEUTRAL. 
Evaporate  to  dryness  over  a  water  bath.     Proceed 

byB. 

B.  —  IT  is  A  SOLID  AND  NEUTRAL. 

Place  some  of  the  solid  substance  in  a  test-tube 
and  add  1 cc  of  cone.  H2SO4 ;  note  results  as 
follows :  — 

1.  Rapid  effervescence  of  an  odorless,  colorless 
gas. 

Try  for  a  carbonate,  Exp.  108 ;  also  pass  the 
gas  through  a  clear  solution  of  Ca(OH)2. 
White  precip.  indicates  a  carbonate.  See  Exps. 
106  and  107. 

2.  Slower  effervescence  of  a  gas  possessing  odor, 
but  not  color : 

(a)  Odor  of  rotten  eggs.    Indicates  sulphide. 
See  Exps.  113  and  114. 

(b)  Odor  of  burning  sulphur  matches.     Indi- 
cates H2SO3  or  H2S2O3.     See  Exps.  115  and  116. 

(<?)  Odor  of  peach  blossoms.  Indicates  HCy. 
See  Exp.  109. 

(d)  Odor  of  vinegar.  Indicates  acetic  acid, 
HC2H3O2.  Prove  it  is  an  acetate  by  dissolving 
the  solid  substance  in  H2O,  adding  some  Fe2Cl6 
and  boiling.  A  red  solution  of  ferric  acetate. 


118        LABORATORY  GUIDE  IN  CHEMISTRY. 

Fe2(C2H3O2)6,  whose  color  is  destroyed  by  HC1 
is  produced,  in  case  the  substance  is  an  acetate. 

(e)  An    irritating     odor    indicates     HNO3, 
Exp.  78  ;  HC1,  Exp.  83 ;  or  HF,  Exp.  95. 

3.  On  warming  gently,  a  gas  having  an  irritat- 
ing odor  and  a  color  indicates  HI,  Exps.  89,  92, 
and   93;    HBr,    Exps.    84   and   88;   or,   HNO2, 
Exp.  69. 

4.  A  crackling  sound  or  sudden  explosion  indi- 
cates   HC1O3.     See    text  for  the    production  of 
chlorine  tetroxide,  C12O4.     Shep.,  p.  101. 

5.  If  none  of   these  acids  are  found,  try  for 
H2SO4,  Exp.  117. 

C.  —  IT  is  A  LIQUID  AND  ACID  :  In  this  case  it 
may  be  a  free  acid  or  an  acid  salt.  Try  the  solution 
directly : 

1.  Try  for  a  sulphate,  H2SO4,  by  first  acidu- 
lating  with    HC1   and    then    proceeding   as   in 
Exp.  117. 

2.  Try  a  fresh  portion  with  HNO3  and  a  drop 
of    AgNO3 :    white   prec.    indicates    HC1 ;    yel- 
lowish  white,    HBr  ;    yellow,    HI  ;     brown    to 
black,  H2S.     Try  as  in  B  for  each  in  turn. 

3.  Try  in  order  as  in  B  for  HNO3,  H2CO3, 
HC2H3O2  and  HC1O3. 

m  ~9      m  o 


NOTE.  —  The  teacher  should  take  care  to  use  only  the  commonest 
compounds  for  the  above  tests. 


120         LABORATORY  GUIDE  IN  CHEMISTRY. 

COMMON  METALLIC  ELEMENTS. 

GROUP   I. 
Lead,  Silver,  and  Mercury. 

Experiment  120.  —  Amalgams,  (a)  Take  in  a  test-tube 
a  small  globule  of  mercury.  Cover  the  mercury  with  a 

1  to  5  solution  of  silver  nitrate,  AgNO3.    (?)    Do  not 
shake  the  tube. 

(6)  Place  in  a  tube  small  pieces  of  copper,  zinc,  and 
iron.  Cover  them  with  a  solution  of  mercurous  nitrate, 
HgNO3.  After  standing  a  few  moments,  examine. 
(?)  Remove  the  metals.  Wipe  them  with  the  finger. 
(?)  Rub  them  a  moment.  (?)  Which  are  perma- 
nently affected  ?  Compare  the  two  experiments,  a  and  b. 

Equations:  (a)  Hg  +  AgNO3  =  HgNO3  +  Ag.  The 
crystals  obtained  are  composed  of  Hg  and  Ag.  (5) 

2  HgNO3  +  Zn  =  Zn  (NO3)2  +  Hg2.     Copper  and  iron 
reactions  are  similar.     Write  them.     In  this  case  the 
mercury  forms  a  coating  on  the  metals,  and  no  crystals. 

Experiment  121.  —  Lead.  Precipitation  by  Means  of  Zinc. 
Place  in  a  test-tube  a  strip  of  metallic  zinc.  Pour  over 
it  about  5  cc  of  a  solution  of  lead  acetate,  Pb(C2H3O2)2. 
Do  not  shake  the  tube.  Note  any  changes.  (?)  Ex- 
amine product  carefully. 

Wash  thoroughly  with  water,  remove  from  the  tube, 
and  scrape  the  deposit  off  the  zinc.  Save  for  testing  in 
Exp.  123.  Complete  the  equation  Pb  (C2H3O2)2  +  Zn 
=  Zn(C2H3O2)2  +  ?  Explain  the  action. 

NOTE.  —  Remember  to  pour  all  solutions  containing  silver  into  a 
receptacle  kept  on  th£  table  for  the  purpose.  Also  never  pour  mercury 
or  mercury  solutions  into  the  sink. 


122        LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  122.  —  Lead.  Preparation  from  Galena  on 
Charcoal.  Place  on  a  piece  of  charcoal  about  .1  gram  of 
pulverized  lead  sulphide,  galena,  PbS.  Cover  with  a 
little  sodium  carbonate,  Na2CO3,  and  heat  in  the  redu- 
cing flame  before  the  blowpipe.  (?) 

Note  appearance  of  globules.  (?)  Remove  the  glob- 
ules and  try  hardness,  malleability,  etc. 

Why  did  you  use  sodium  carbonate  ?  Give  properties 
of  lead  noted. 

Experiment  123.  —  Tests  for  Lead  in  Solution.  Place 
the  product  of  Exp.  121  in  a  tube ;  cover  it  with  dilute 
nitric  acid  and  warm.  Why?  As  soon  as  action 
ceases  dilute  with  about  10 c  c  of  water. 

Now  divide  the  solution  into  five  parts,  and  treat  as 
follows:  To  one,  add  hydrogen  sulphide.  (?)  To 
second,  potassium  bichromate.  (?)  To  third,  ammo- 
nium carbonate.  (?)  To  fourth,  potassium  iodide. 
(?)  To  fifth,  sulphuric  acid.  (?) 

The  precipitates  should  be  black,  yellow,  white,  yellow 
and  white  in  order.  (?) 

Name  the  products  and  write  the  equations. 

Experiment  124.  —  Silver.  Precipitation  by  Zinc.  Treat 
a  strip  of  metallic  zinc  with  about  lcc  of  a  solution  of 
silver  nitrate,  just  as  in  Exp.  121.  (?)  Compare 
results.  (?) 

Save  the  product  as  before,  for  use  in  testing  for 
silver.  Complete  the  equation  2AgNO3  +  Zn  =  ?  -+-  ? 

Experiment  125.  —  Silver.  Precipitation  by  Chloral  Hy- 
drate. Take  about  1 c  c  of  silver  nitrate  solution  in  a 
tube.  Add  two  drops  of  chloral  hydrate  solution,  and 
make  alkaline  with  a  drop  of  ammonia. 


124        LABORATORY  GUIDE  IN  CHEMISTRY. 

Heat  the  tube,  rolling  it  in  the  fingers  until  a  brignt 
coating  appears.  What  is  it?  Chloral  hydrate  is  a 
reducing  agent.  What  action  has  taken  place  ? 

Since  silver  is  soluble  in  nitric  acid,  suggest  a  good 
way  to  clean  your  tube.  (?) 

Experiment  126.  —  Silver.  Tests  for  Silver  in  Solution. 
Dissolve  the  product  of  Exp.  124  in  dilute  nitric  acid 
and  add  enough  water  to  make  about  10 cc  of  the  solu- 
tion. To  one-half 'of  the  solution  add  about  two  drops 
of  hydrochloric  acid.  (?)  Compare  Exp.  83.  (?) 

Divide  the  precipitate  into  two  parts:  Try  one  with 
nitric  acid  (  ?  )  ;  the  other  with  ammonia.  (?) 

Through  the  remainder  of  the  solution  of  silver,  pass 
hydrogen  sulphide.  (?)  Divide  the  precipitate  into 
two  parts  :  Try  one  with  potassium  cyanide,  (  ? )  ;  the 
other  with  cone,  nitric  acid.  (?) 

Experiment  127.  —  Mercury.  Precipitation  by  Zinc.  Treat 
a  small  piece  of  metallic  zinc  with  about  1 c  c  of  mercu- 
rous  nitrate  Hg2  (NO3)2  as  in  Exps.  121  and  124. 

Compare  the  product  with  the  corresponding  ones 
with  lead  and,  silver.  (?)  May  they  be  easily  dis- 
tinguished in  this  way?  Complete  the  equation 
Hg2(NO3)2  +  Zn  =  ?  +  ?  Save  the  product  for  the 
test  in  Exp.  128. 

Experiment  128.  —  Mercury.  Test  for  "  ous"  Mercury  in 
Solution.  Carefully  wash  the  mercury  obtained  in  Exp. 
127  and  wipe  and  remove  the  zinc  remaining.  Dissolve 
the  mercury  in  a  little  dilute  nitric  acid.  (?)  Make 
it  up  to  about  5 c  c  with  H2O. 

Add  two  or  three  drops  of  hydrochloric  acid.  (?) 
Filter  the  precipitate  and  wash  on  the  filter  with  a  few 
drops  of  ammonia.  (?)  Compare  Exp.  126,  first  part. 


126        LABORATORY  GUIDE  IN  CHEMISTRY. 

What  is  the  action  and  what  the  black  substance 
produced  ?  Could  you  distinguish  silver  and  mercury 
in  this  way? 

Experiment  129.  —  Separation  of  Metals  of  Group  I.  in  the 
same  Solution. 

Part  I.  Take  in  a  tube  about  10 c  c  of  the  solution 
containing  the  metals.  Add  hydrochloric  acid,  by  the 
drop,  as  long  as  a  precipitate  forms.  Color? 

Filter  and  wash  the  precipitate  with  a  little  cold  water. 
Why  not  much  H2O?  The  nitrate  may  be  thrown 
away.  Why? 

The  precipitate  is  composed  of  the  chlorides  of  the 
three  metals.  See  Exps.  126  and  128,  and  remarks  on 
the  precipitation  of  lead  by  hydrochloric  acid,  in  text. 

Part  II.  Wash  the  precipitate  well  with  hot  water,  and 
catch  the  filtrate  in  a  clean  tube.  Lead  chloride  is  solu- 
ble in  hot  water.  Hence  it  will  be  found  in  the  filtrate. 
The  remaining  precipitate  will  be  disposed  of  in  Part  III. 

Divide  the  filtrate  into  three  parts  ;  try  with  potassium 
bichromate,  (?)  potassium  iodide,  (?)  and  sulphuric 
acid.  (?) 

Precipitates  should  be  formed  in  each  case  correspond- 
ing with  those  of  Exp.  123.  Does  this  prove  sufficiently 
the  presence  of  lead  ? 

Part  ffl.  Place  the  filter  with  the  precipitate  in- 
soluble in  hot  water,  over  a  clean  tube,  and  wash  well 
with  2CC  or  3CC  of  ammonia.  See  Exps.  126  and 
128.  (?) 

The  silver  chloride  dissolves  and  filters  through,  while 
the  black  deposit  remaining  on  the  filter  is  sufficient 
proof  of  the  presence  of  mercury. 


128         LABORATORY  GUIDE  IN  CHEMISTRY. 

It  remains  to  show  that  the  silver  is  present  in  the 
filtrate.  Add,  by  the  drop,  strong  nitric  acid  until  a 
change  is  noted.  (?)  Explain  by  reference  to  Exp. 
126. 

A  reappearance  of  the  familiar  white  precipitate  of 
Exps.  83  and  126  is  proof  of  the  presence  of  silver. 

GROUP   II. 

Arsenic,  Tin,  and   Copper.1 

Experiment  130.  —  Arsenic.     Preparation  from  the  Oxide. 

Make  a  small  ball  of  arsenic  trioxide,  As2O3,  with  pow- 
dered charcoal  and  a  drop  of  water. 

Place  the  mixture  in  a  tube  closed  at  one  end,  made 
by  heating  the  end  of  a  short  glass  tube  (about  three 
inches  long)  in  the  gas  flame  until  it  melts  and  closes. 

Heat  carefully  and  strongly.  Examine  the  inner 
surface  of  the  tube.  (?)  Note  the  odor,  if  any.  Do 
not  inhale  the  vapor  freely.  (?) 

Experiment  131.  —  Arsenic.  Marsh's  Test.  Arrange  to 
generate  hydrogen  by  the  action  of  pure  zinc  and  dilute 
H2SO4,  in  a  test-tube  fitted  with  a  delivery  tube  and  jet. 

Before  adding  the  H2SO4,  put  into  the  tube  with  the 
zinc  and  water  three  or  four  drops  of  a  solution  of 
arsenic  acid,  H3AsO4. 

Pour  in  the  H2SO4  and  pass  the  gas  through  the 
apparatus  until  air  is  entirely  expelled.  (?)  Now 
light  the  gas  issuing  from  the  jet,  and  bring  in  contact 
with  the  flame  a  cold  piece  of  porcelain.  A  bright  gray- 

1  For  other  metals  of  this  and  following  groups,  see  Shepard. 

NOTE.  —  As  hydrogen  arsenide  is  a  highly  poisonous  gas,  it  would  be 
safest  to  have  only  one  generator,  and  that  in  the  gas  chamber.  Any 
number  of  spots  may  be  obtained  from  it. 


130        LABORATORY  GUIDE  IN   CHEMISTRY. 

ish  spot  or  mirror  appears  on  the  porcelain.  It  is 
metallic  arsenic. 

Produce  several  spots  and  immediately  stop  the  action 
by  washing  out  the  contents  of  the  tube. 

The  action  is  thus  explained:  Nascent  hydrogen  acts 
upon  the  arsenic  acid,  producing  a  gas  highly  poison- 
ous and  inflammable,  hydrogen  arsenide,  AsH3.  This 
gas  burns  along  with  the  hydrogen  evolved  from  the 
zinc  and  H2SO4,  and  when  the  cold  porcelain  surface  is 
brought  to  the  flame,  the  arsenic  is  cooled  below  the 
point  of  ignition  and  deposited  as  a  mirror.  Compare 
Exp.  83. 

Proceed  to  test  the  spots  as  follows  :  (a)  Moisten  one 
with  (NH4)2S2  ;  it  turns  yellow. 

(6)  Add  a  drop  of  HC1  to  another ;  it  does  not 
dissolve. 

(tf)  Treat  another  spot  with  a  drop  of  a  solution  of 
chlorine  in  KOH  ;  it  dissolves. 

(d)  To  another  add  hot  HNO3;  it  dissolves  clear. 
To  the  clear  solution  add  a  drop  of  AgNO3 ;  no  change. 
Now  allow  vapor  of  NH3  to  come  in  contact  with  the 
solution  ;  it  turns  brick  red  or  yellow. 

These  tests  completely  identify  the  arsenic,  as  anti- 
mony, which  also  forms  spots  similar  to  the  arsenic 
spots,  gives  slightly  different  results  with  the  same  treat- 
ment. Compare  text  on  antimony. 

Experiment  132.  —  Tin.  Precipitation  by  Zinc.  Treat  a 
strip  of  metallic  zinc  with  5CC  of  a  solution  of  stannous 
chloride,  SnCl2,  just  as  in  the  preparation  of  lead, 
silver,  and  mercury.  (?)  Compare  Exps.  121,  124, 
and  127.  (?)  Mention  any  properties  of  tin  noted. 

Could  crystals  of  lead,  silver,  and  tin  precipitated  by 


132         LABORATORY  GUIDE  IN  CHEMISTRY. 

zinc  be  distinguished  by  their  form,  color,  and  general 
characters?  Save  the  product  to  test  for  tin  in  the 
next  experiment. 

Experiment  133.  —  Tests  for  Tin.  Remove  the  crystal- 
line deposit  obtained  in  Exp.  132  from  the  zinc  ;  wash 
thoroughly  with  H2O,  and  dissolve  in  the  least  possible 
amount  of  dilute  HC1.  Heat  if  necessary.  Dilute 
with  H2O  to  10  cc. 

Take  5CC  of  the  solution  in  each  of  two  tubes.  To 
one  add  a  drop  of  mercuric  chloride,  HgCl2.  If  tin  is 
present  in  "  ous  "  condition,  a  white  precipitate,  which 
soon  turns  black,  will  follow  ;  if  in  "  ic  "  condition,  no 
change.  (?) 

Through  the  second  part,  pass  hydrogen  sulphide, 
H2S.  A  stannous  salt  yields  a  brown  precipitate,  SnS; 
a  stannic  salt,  a  yellow  precipitate,  SnS2.  What  is  the 
character  of  the  solution,  "  ous  "  or  "  ic  "  ? 

Experiment  134.  —  Copper,    Precipitation  by  Iron.     Put 

a  piece  of  bright  iron  wire  in  a  test-tube,  and  pour  over 
it  a  solution  of  copper  sulphate,  CuSO4.  (?) 

Remove  and  examine  the  wire.  (?)  Give  some 
properties  of  copper  noted.  Complete  the  equation 


Experiment  135.  —  Copper.  Eeduction  on  Charcoal.  Treat 
some  powdered  copper  sulphate  on  charcoal  with  sodium 
carbonate,  in  the  reducing  flame.  (?) 

It  is  difficult  to  obtain  clear  beads,  but  small  particles 
of  the  red-brown  mass  resulting  may  be  washed  with 
H2O,  and  dissolved  in  the  least  possible  amount  of 
dilute  HNOo.  Color  of  the  solution  ?  Save  this  solu- 

o 

tion  to  test  for  copper  in  the  following  experiments. 


134        LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  136.  —  Copper.  The  Bead  Test.  Prepare  a 
borax-bead  on  a  platinum  loop,  just  as  before.  Dip  the 
bead  while  hot  into  the  solution  to  be  tested,  and  heat 
in  the  oxidizing  flame  before  the  blowpipe.  > 

If  the  copper  is  present  the  bead  will  be  green  while 
hot,  blue  when  cold.  (?) 

Now  heat  the  bead  in  the  reducing  flame.     (?) 

Experiment  137.  — Copper.  Tests  in  the  Wet  Way. 
Dilute  the  solution  remaining  from  Exps.  135  and  136 
to  about  10 c  c.  Divide  into  three  parts. 

To  one,  add  two  to  ten  drops  of  ammonia  until  changes 
cease.  ( ?  ) 

Through  the  second,  pass  hydrogen  sulphide.  (?) 
Compare  the  two  resulting  products.  Give  a  distinc- 
tion between  solutions  and  precipitates.  (?) 

To  the  third,  add  one  or  two  drops  of  potassium  fer- 
rocyanide,  K4FeCy6.  If  copper  is  present  in  small 
quantity,  a  reddish-brown  solution  is  formed ;  if  plenti- 
ful, a  precipitate  of  the  same  color.  (?) 

GROUP  III. 
Iron,  Chromium,  Aluminum,  Nickel,  Cobalt,  and  Zinc. 

Experiment  138.  — Iron.  Tests  for  "ous"  and  "ic" 
Salts  in  Solution.  Both  ferrous  and  ferric  salts  are  tested 
by  the  same  reagents.  The  condition  of  the  salt  is  de- 
termined by  the  action  of  the  reagents,  producing  results 
peculiar  to  each  condition. 

Prepare  a  solution  of  a  ferrous  salt  by  dissolving  a 
small  clear  green  crystal  of  ferrous  sulphate,  FeSO4, 
in!0cc  of  coldH2O. 

Divide  into  four  parts.     To  the  first  add  one  drop  of 


136         LABORATORY  GUIDE  IN  CHEMISTRY. 

potassium  sulphocyanide,  KCyS.  (?)  To  the  second, 
one  drop  of  potassium  ferrocyanide,  K4FeCy6.  (?) 
To  the  third,  one  drop  of  potassium  ferricyanide, 
K3FeC3v  (?)  To  the  fourth,  add  one  or  two  dreps 
of  cone.  HNO3,  and  boil  for  a  moment.  Any  change 
noticed  ? 

When  cool,  divide  into  three  parts  and  add  a  drop  of 
the  same  reagents  as  before,  noting  carefully  each  re- 
sult. (?) 

Now  treat  a  solution  of  ferric  chloride,  Fe2Cl6,  with 
the  three  reagents,  omitting  the  use  of  HNO3.  Com- 
pare with  tjae  preceding  results.  (?) 

What  effect  does  HNO3  have  on  an  "  ous  "  salt  of 
iron? 

Devise  a  table  for  record  of  results  so  that  a  compari- 
son will  be  easy.  The  equations  are  difficult. 

Experiment  139.  —  Chromium.  The  Bead  Test.  Dip  the 
hot  borax-bead  into  a  solution  of  potassium  chromate, 
K2CrO4,  or  of  potassium  bichromate,  K2Cr2O7,  and  heat 
in  the  oxidizing  flame  before  the  blowpipe.  Chromium 
colors  the  bead  green.  (?) 

Experiment  140.  —  Chromium.  Tests  for  Chromium  in  the 
Wet  Way.  Divide  the  solution  into  three  parts. 
Through  the  first  pass  H2S.  (?)  To  the  second  add 
Pb(C2H3O2)2.  (?)  To  the  third,  AgNO3.  (  ?  ) 

The  products  should  be  in  order,  a  green  solution,  a 
yellow  precipitate,  and  a  red  precipitate.  The  two 
precipitates  are  PbCrO4  and  Ag2CrO4,  lead  and  silver 
chromates. 

Write  reactions  for  these  on  the  supposition  that  the 
chromium  was  present  as  potassium  chromate. 


138         LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  141.  —  Test  for  Aluminum  in  Solution.  Take 
5CC  of  the  solution  to  be  tested.  Add  one  drop  of 
HC1.  (  ?  )  Now  pass  H2S  for  a  moment.  (  ?  ) 

Should  any  change  be  produced  up  to  this  time  it  is 
caused  by  the  presence  of  metals  of  the  first  and  second 
groups,  which  must  be  thoroughly  precipitated  and  fil- 
tered off  before  proceeding. 

Boil  to  expel  the  excess  of  H2S.  (The  tube  should 
no  longer  smell  of  the  gas.)  In  case  first  and  second 
groups  are  known  to  be  absent,  the  preceding  steps 
may  be  omitted. 

Add  1 c  c  to  2 c  c  of  a  solution  of  ammonium  chloride, 
NH4C1,  and  then  add  ammonia,  NH4OH,  a  drop  at  a 
time,  until  on  shaking  the  solution  smells  of  ammonia. 

The  appearance  of  a  white,  gelatinous  precipitate  of 
aluminum  hydroxide,  A12(OH)6  is  proof  of  the  presence 
of  aluminum. 

Experiment  142.  —  To  Separate  and  Identify  Iron,  Chro- 
mium, and  Aluminum  in  the  same  Solution.  Take  10  c  c  of 
the  solution,  add  two  drops  of  HC1.  Pass  H2S.  Fil- 
ter if  necessary  to  remove  Groups  I.  and  II. 

Boil  until  the  solution  no  longer  smells  of  H2S.  Add 
two  drops  of  cone.  HNO3  and  boil  for  a  moment.  (?) 
Compare  Exp.  138.  (?) 

Add  NH4OH  until  the  solution  is  alkaline.  Now 
add  lcc  of  NH4C1.  (?)  The  precipitate  contains 
Fea(OH)6,  Cra(OH)6  and  A12(OH)6. 

Colors  red,  green,  and  white.     Filter  and  wash. 

Make  a  hole  in  the  bottom  of  the  filter,  and  wash  the 
precipitate  through  into  a  clean  tube.  Decant  to  5CC. 

Add  1 c  c  of  KOH  and  boil  for  some  minutes.  The 
A12(OH)6  dissolves.  Filter. 


140         LABORATORY  GUIDE  IN  CHEMISTRY. 

Treat  the  filtrate  with  HC1  to  acid  reaction,  then  add 
NH4OH  and  NH4C1  as  before.  Aluminum  hydroxide  is 
precipitated.  Compare  Exp.  141. 

The  precipitate  of  iron  and  chromium  hydroxides 
obtained  above  is  now  treated  for  iron  and  chro- 
mium as  follows  :  One-half  the  paper  with  its  precipitate 
is  washed  with  dilute  HC1.  The  precipitate  dissolves. 
Test  this  for  iron  as  in  Exp.  138.  (?) 

The  remainder  of  the  precipitate  with  the  accompany- 
ing paper  is  put  on  a  piece  of  platinum  foil,  covered 
with  a  mixture  of  equal  parts  of  KNO3  and  Na2CO3  and 
fused  in  the  Bunsen  flame. 

On  cooling  it  is  found  to  be  tinged  yellow,  caused  by 
the  oxidation  of  the  chromium  to  the  form  of  a  chromate. 

Remove  the  mass  and  dissolve  in  occ  of  H2O.  Acid- 
ulate with  acetic  acid,  and  add  one  drop  of  lead  acetate 
solution.  (?)  Compare  Exp.  140.  (?) 

Experiment  143.  —Nickel.  The  Bead  Test.  Dip  the  hot 
borax-bead  into  the  solution,  which  will  in  most  cases  be 
greenish  in  color,  and  heat  in  the  oxidizing  flame  before 
the  blowpipe.  The  bead  becomes  brownish-red  while 
hot,  yellow  when  cold.  (?) 

This  test  is  obscured  by  the  presence  of  cobalt.  See 
Exp.  145.  The  reducing  flame  produces  a  grayish  color, 
owing  to  the  reduction  to  metallic  nickel.  (?) 

Experiment  144.  —  Nickel.  Tests  in  the  Wet  Way.  Take 
5CC  of  the  solution  to  be  tested;  add  two  drops  of 
NH4OH.  (?)  The  apple-green  precipitate  is  Ni  (OH)2. 
Now  add  an  excess  of  NH4OH.  (?)  Compare  the 
test  for  copper,  Exp.  137.  (  ?  )  Now  add  KOH.  (  ?  ) 

To  a  second  portion  of  the  original  solution  add 
KOH.  (?)  Compare  the  reactions  with  NH4OH.  (?) 


142        LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  145.  —  Cobalt.  The  Bead  Test.  Dip  the  hot 
borax  bead  into  the  solution  to  be  tested,  and  heat  in 
the  oxidizing  flame.  (?) 

All  cobalt  salts  produce  blue  beads.  Compare  Exp. 
39.  (?) 

Experiment  146.  —  Cobalt.  "  Sympathetic  Ink."  Write 
on  a  piece  of  glazed  paper  with  a  solution  of  cobaltous 
nitrate,  Co(NO3)2.  (?)  Allow  to  dry  and  then 
warm.  (?) 

Hydrated  cobalt  salts  are  pink  in  color;  anhydrous 
salts  are  violet.  Account  for  the  changes  noted. 

Experiment  147.  —  Zinc.  The  Blowpipe  Test.  Powder 
the  solid  to  be  tested,  mix  with  sodium  carbonate,  Na2CO3, 
and  heat  in  the  oxidizing  flame  before  the  blowpipe  on 
charcoal.  A  coating  of  oxide  will  be  formed  around 
the  assay,  yelloiv  while  hot,  white  when  cold.  (?) 

Touch  the  coating  with  a  rod  moistened  with  a  solu- 
tion of  cobaltous  nitrate,  Co(NO3)2.  Heat  again  in  the 
oxidizing  flame.  (?) 

The  product  is  a  pigment  (?)  and  its  production 
here  is  proof  of  the  presence  of  zinc. 

GROUP   IV. 
Barium,  Strontium,  and  Calcium. 

Experiment  148.  —  Barium.  Flame  and  Spectrum  Tests. 
Moisten  a  clean  platinum  wire  with  a  strong  solution  of 
a  barium  salt  and  put  into  the  non-luminous  flame.  (?) 
The  predominating  color  of  the  barium  flame  is  green. 

Examine  the  flame  with  the  spectroscope.  (?)  The 
sifting  of  the  rays  of  different  tinge  reveals  the  presence 
of  the  other  colors. 


144         LABORATORY  GUIDE  IN  CHEMISTRY. 

The  bright  yellow  indicative  of  sodium  is  generally 
present  in  all  spectrum  tests. 

Name  and  locate,  with  the  assistance  of  the  luminous 
scale,  the  bright  lines  of  the  barium  spectrum. 

Experiment  149,  —  Barium.     Tests  in  the  Wet  Way.     A 

soluble  barium  salt  may  be  tested  for  as  follows  : 

(a)  To  one  portion  of  the  solution  add  K2Cr2O7  and 
NH4OH.  (?)  Barium  chromate,  BaCrO4  is  yellow. 
(?)  Compare  tests  for  lead,  Exp.  123.  (?)  This 
precipitate  should  be  insoluble  in  HC2H3O2.  (?) 

(£)  To  a  second  portion,  add  H2SO4.  (?)  Try 
its  solubility  in  acids.  (?)  Barium  sulphate  is  white. 
Compare  test  for  a  sulphate,  Exp.  117. 

Try  to  filter  it.  (?)  Barium  sulphate  is  difficult  to 
filter,  owing  to  the  exceeding  fineness  of  the  particles. 

(e)  To  a  third  portion  add  one  drop  of  a  clear  solu- 
tion of  CaSO4.  (?)  Compare  the  precipitate  with 
that  obtained  in  b.  (?)  It  should  be  the^ame. 

Experiment  150.  —  Strontium.  Flame  and  Spectrum  Tests. 
Treat  a  strontium  salt  solution  precisely  as  in  Exp. 
148.  (?) 

Name  and  locate  the  bright  lines. 

Experiment  151.  —  Green  and  Ked  Fire.  Mix  intimately 
one  part  powdered  barium  nitrate,  Ba(NO3)2,  one  part 
powdered  potassium  chlorate,  KC1O3,  and  J  part  flowers 
of  sulphur.  Ignite  with  a  match.  (?) 

Repeat  the  experiment,  using  instead  of  the  Ba(NO3)2, 
an  equal  quantity  of  powdered  Sr(NO3)2.  (?) 

To  what  are  the  colors  due?  Why  are  the  KC1O3 
and  sulphur  used.  (?) 

NOTE,  —  Powdered  shellac  may  be  substituted  for  sulphur  in  Exp.  151. 


146         LABORATORY  GUIDE  IN  CHEMISTRY. 

Experiment  152.  —  Calcium.  Flame  and  Spectrum  Tests. 
Treat  a  calcium  salt  solution  as  in  Exps.  148  and 
150.  (?) 

Name  and  locate  the  lines. 


GROUP  V. 

Potassium  and  Sodium. 

Experiment  153.  —  Potassium.  Its  Affinity  for  Water. 
Carefully,  by  means  of  nippers,  drop  a  piece  of  metallic 
potassium  in  water  in  a  dish.  (?)  Look  at  the  flame 
through  a  blue  glass.  (?) 

All  potassium  salts  and  the  metal  itself  color  the 
flame  violet.  Try  the  water  with  litmus  paper.  (?) 

Never  handle  potassium  and  sodium  with  the  fingers. 
Why?  Complete  the  equation  H2O  +  K  =  KOH  +  ? 
Compare  Exp.  49. 

The  color  of  the  flame  is  caused  by  the  heat  of  the 
reaction  igniting  the  evolved  hydrogen,  which  in  turn 
vaporizes  some  of  the  potassium  which  burns  with  the 
characteristic  color,  forming  an  oxide,  K2O. 

Experiment  154.  —  Potassium.  Flame  and  Spectrum  Tests. 
Try  a  potassium  salt  solution  as  before  with  the  flame 
and  spectroscope.  (?) 

Name  and  locate  the  bright  lines. 

NOTE.  —  The  violet  line  is  difficult  to  get. 

Experiment  155.  —  Sodium.  Comparison  with  Potassium. 
Drop  a  piece  of  metallic  sodium  into  a  dish  of  water. 
(?)  Compare  Exp.  153.  (?) 

Repeat  the  experiment,  using  hot  water.  (?)  Is 
potassium  more  or  less  active  than  sodium  ?  Explain. 


148         LABORATORY  GUIDE  IN  CHEMISTRY. 

Try  the  water  with  litmus  paper.     (?) 

Why  do  sodium  and  potassium  float  on  water  ?  Com- 
pare properties  of  sodium  and  potassium. 

Experiment  156.  —  Sodium.  Flame  and  Spectrum  Tests. 
Examine  the  sodium  salt  solution  as  before. 

Name  and  locate  the  bright  lines. 


APPENDIX 


TABLE   OF   BEFEBENCES. 


REFERENCE  BOOKS.  ABBREVIATION. 

Shepard's  Chemistry  .     .     .     .     ...     .     .     .  Shep. 

Att field's  Chemistry Att. 

Fresenius's  Qualitative Fre. 

Fresenius's  Quantitative Fre.  Q. 

Remsen's  Briefer  Course Rem. 

Richter's  Chemistry .     .     .    .     .  Rich. 

Wagner's  Technology Wag. 

Gage's  Elements  of  Physics      .......  Gage. 

Dana's  Text-Book  of  Geology Da. 


References  by  Experiments. 


EXP. 
EXP. 
EXP. 
EXP. 
EXP. 

11. 

EXP.  7 
EXP.  8- 

317. 

EXP.  9 
EXP.  10 
EXP.  11 
EXP.  12 
EXP.  13 
EXP.  14 
EXP.  15 

149. 

EXP.  16 
EXP.  17 
EXP.  18 


Fre.  Q.  P.  30. 

Gage  P.  9. 

Att.  P.  91. 

Da.  P.  27  and  31. 

Gage  P.  9  ;  also  Exp. 

Att.  P.  36. 

Att.  P.  115  ;  Shep.  P. 

Att.  P.  84. 

Rich.  P.  9*0  ;  Fre.  P.  4. 

Fre.  P.  15. 

Fre.  P.  5. 

Fre.  P.  8. 

-  Att.  P.  106  ;  Fre.  P.  9. 
-Fre.  P.  11  ;  also  Exp. 

-  Shep.  P.  9. 
-Shep.  P.  10. 

-  Shep.  P.  172. 


EXP.  19  —  Shep.  P.  11. 

EXP.  20  —  Shep.  P.  325. 

EXP.  21  —  Att.  P.  143. 

EXP.  22  —  Shep.  P.  23. 

EXP.  23  —  Shep.  P.  23  ;  Rem.  P. 
41. 

EXP.  24  —  Att.  P.  17  ;  Rem.  P. 
10. 

EXP.  25  —  Explanation  of  the 
action  of  MnO2  :  It  either 
remains  unchanged  or  under- 
goes a  double  change  acting 
as  a  carrier  in  freeing  the 
KClO3of  its  oxygen.  Such 
action  has  been  called  "  ca- 
talysis." 

EXPS.  26, 27,  and  28-Shep.  P. 25. 

EXP.  29  —  Shep.  P.  317. 

EXP.  30  — Shep.  P.  27;  Att.  P. 
23. 

EXP.  31  —  Shep.  P.  27. 

EXP.  32  —  Shep.  P.  27. 


153 


154 


APPENDIX. 


EXP.  33  —Wag.  P.  618;  Att.  P. 

30. 

EXP.  34  — Rem.  P.  51-3. 
EXP.  35  —  Gage,  P.  145. 
EXP.  37  —  Shep.  P.  28;  Rich.  P. 

293;  Rem.  P.  199. 
EXP.  38— Shep.  P.  29;  Rem.  P. 

198. 
EXP.  39  —  Rem.  P.  201 ;  Shep. 

P.  282. 

EXP.  40  —  Rem.  P.  52. 
EXP.  41  — Rem.  P.  196;  Att.  P. 

23. 

EXP.  42— Rem.  P.  196;  Att.  P.  23. 
EXP.  44— Rem.  P.  53;  Att.  P. 

155,  Note  1. 
EXP.  45  —  Shep.  P.  31 ;  Rem.  P. 

91. 

EXP.  46  —  Shep.  P.  31. 
EXP.  47  —  Att.  P.  86. 
EXP.  49  — Shep.  P.  35;  Att.  P. 

94;  Rem.  P.  59. 
EXP.  50  —  Rem.  P.  65 ;  Shep.  P. 

37;  Att.  P.  20. 
EXP.  51— Att.  P.  21. 
EXP.  54  —  Rem.  P.  77. 
EXP.  55  —  Wag.  P.  646. 
EXP.  56  — Rem.  P.  77;  Shep.  P. 

40. 

EXP.  57  —  Shep.  P.  35. 
EXP.  58  —  Rem.  P.  72. 
EXP.  59  — Rem.  P.  127;  Shep. 

P.  50. 
EXP.  60  —  Shep.  P.  51 ;  Rem.  P. 

131. 
EXP.  61  — Rem.  P.  139;  Shep. 

P.  52. 

EXP.  62  —  Shep.  P.  52. 
EXP.  63  —  Shep.  P.  55. 
EXP.  64  —  Shep.  P.  58. 
EXP.  65  — Att.  P.  94;  Rem.  P. 

117. 


EXP.  66  — Shep.  P.  59;  Rem.  P. 

157. 
EXP.  67  —  Shep.  P.  60;  Rem.  P. 

158. 
EXP.  68  —  Shep.  P.  61 ;  Rem.  P. 

158. 

EXP.  69  —  Shep.  P.  63. 
EXP.  70  —  Shep.  P.  64. 
EXP.  71  —  Shep.  P.  67;  Rem.  P. 

148. 

EXP.  72  — Shep.  P.  68;  Rem.  P. 
152. 

EXP.  73  — Shep.  P.  69;  Rem.  P. 

310;  Wag.  P.  148. 
EXP.  74  —  Shep.  P.  69. 
EXP.  75  —  Shep.  P.  69. 
EXP.  76  —  Wag.  P.  160. 
EXP.  77  — Shep.  P.  70;  Att.  P. 

285. 
EXP.  78  — Shep.  P.  70;  Att.  P. 

286. 
EXP.  79  — Shep.  P.  92;  Att.  P. 

29;  Rem.  P.  98. 
EXP.  80— Shep.  P.  93  and  95: 

Rem.  P.  101. 
EXP.  81  — Shep.  P.  96. 
EXP.  82  —  Shep.  P.  97;  Hem.  P. 

103. 

EXP.  83  —  Shep.  P.  99. 
EXP.  84  — Shep.  P.  109;  Rem. 

P.  237. 

EXPS.  85  and  86  — Shep.  P.  110. 
EXP.  87  —  Shep.  P.  110;  Att.  P. 

268. 

EXP.  88  —  Att.  P.  268. 
EXP.  89  — Shep.  P.  116;  Rem. 

P.  240. 
EXP.  90  — Shep.  P.  117;  Att.  P. 

271. 

EXP.  91  — Shep.  P.  118. 
EXP.  92  — Shep.  P.  119;  Att.  P. 

271. 
EXP.  93  —  Att.  P.  271. 


APPENDIX. 


155 


EXP.  94  — 

273. 
EXP.  95  — 

P.  243. 
EXP.  96  — 
EXP.  97  — 
EXP.  98- 
EXP.  99  — 

P.  645. 
EXPS.  101 

135. 

EXP.  103  - 
EXP.  104- 
EXP.  105  - 
EXP.  106  - 
EXP.  107- 

P.  181. 
EXP.  108- 
EXP.  109  - 

P.  205. 
EXP.  110 

P.  248. 
EXP.  111- 
EXP.  112  - 

P.  252. 
EXP.  113 

P.  252. 
EXP.  114  - 
EXP.  115- 

P.  257. 
EXP.  116- 
EXP.  117  - 
EXP.  118- 

P.  267. 
EXP.  119- 
EXP.  120- 

P.  192. 
EXP.  121 


Shep.  P.  119  ;  Att.  P. 
Shep.    P.    122;    Rem. 

Shep.  P.  130. 
Shep.  P.  132. 
Shep.  P.  133. 
Shep.  P.  135;  Wag. 

and  102  — Shep.  P. 

Shep.  P.  136. 
Shep.  P.  140. 
Shep.  P.  140  and  142. 
Shep.  P.  138. 
Shep.  P.  138;  Rem. 

Da.  P.  36-7. 

Shep.  P.  146;  Rem. 

—  Shep.  P.  158;  Rem. 

Rem.  P.  249. 

Shep.  P.  158;  Rem. 

—  Shep.  P.  160;  Rem. 

Shep.  P.  163. 
Shep.  P.  164;  Rem. 

Shep.  P.  166. 
Shep.  P.  173. 
Shep.  P.  197;  Rem. 

-Shep.  P.  204-206. 
-Shep.  P.  211;  Att. 


—  Shep.  P.  225. 


EXP.  122  —  Shep.  P.  225 ;  Rem. 

P.  365. 

EXP.  123  —  Shep.  P.  228. 
EXP.  124  — Shep.  P.  229;  Rem. 

P.  341. 

EXP.  125  — Shep.  P.  229. 
EXP.  126  —  Shep.  P.  233. 
EXP.  127  — Shep.  P.  234. 
EXP.  128  —  Shep.  P.  235. 
EXP.  129  —  Shep.  P.  239. 
EXP.  130  —  Shep.  P.  242. 
EXP.  131  — Shep.  P.  246;  Rem. 

P.  271. 

EXP.  132  —  Shep.  P.  252. 
EXP.  133  —  Shep.  P.  253. 
EXP.  134  —  Shep.  P.  259. 
EXP.  135  — Shep.  P.  261;  Rem. 

P.  335. 

EXPS.  136  and  137— Shep.  P.  261. 
EXP.  138  —  Shep.  P.  281. 
EXP.  139  —  Shep.  P.  285. 
EXP.  140  —  Shep.  P.  285. 
EXP.  141  —  Shep.  P.  288. 
EXP.  142  —  Shep.  P.  289. 
EXPS.  143  and  144  — Shep.  P. 

292. 
EXPS.  145  and  146  — Shep.  P. 

294;  Att.  P.  231. 
EXP.  147  —  Shep.  P.  300. 
EXP.  148  —  Shep.  P.  312. 
EXP.  149  — Shep.  P.  311. 
EXP.  150  —  Shep.  P.  313. 
EXP.  152  —  Shep.  P.  316. 
EXP.  153  —  Shep.  P.  321. 
EXP.  154  — Shep.  P.  326. 
EXP.  155  —  Shep.  P.  328. 
EXP.  156  —  Shep.  P.  333. 


156 


APPENDIX. 


TABLE   OF   WEIGHTS   AND   MEASURES. 


ENGLISH   WEIGHTS. 
Avoirdupois  Weight. 


POUND. 

OUNCES. 

DRACHMS. 

GRAINS 

1 

.     .     16     .     .     , 

,     .     .     256     .     . 

7000 

1 

16 

.  .  .437.5 

1  .  . 

.    27.3495 

1 

GRAMMES. 

453.5926 

28.3495 

1.7718 

.0648 


Troy  Weight. 


POUND. 
1          . 

OUNCES. 
.     .     12          . 

PENNYWEIGHT. 
.     .    .     240          .     . 

GRAINS. 

.  5760  . 

GRAMMES. 

.  .  373.2419 

1 

20 

.     480  . 

.  .     31.1035 

1 

24  . 

.  .       1.5552 

1  . 

.0648 

METRIC    MEASURES. 
Measures  of  Weight. 


1  milligram  (mg) 
1  centigram  (cg) 
1  decigram  (dg) 


0.001  gram 
0.010  gram 


about  -fa  of  grain. 


gram 


(g) 


=  0.100  gram. 

=  1.000  gram  =  15.4323  grains. 


1  liter  ^ 
1  quart 
1  meter (m) 
1  inch 


Equivalents. 

=  1.0567  quarts. 

=  .9463  liters. 

=  39.3708  inches. 

=  2.54  centimeters  (cm). 


APPENDIX. 


157 


A   TABLE    OF   THE   PRINCIPAL   ELEMENTS. 


ELEMENTS. 

AT. 
WT. 

SYM. 

VAL. 

SP.  G. 

CONDITION. 

g       f  Oxygen 

16 

O 

2 

1.105 

Gas. 

Jttj 

Nitrogen 

14 

N 

1,3,5 

0.971 

Gas. 

t  *- 

Chlorine 

35.5 

Cl 

1 

2.45 

Gas. 

£* 

Bromine 

79.8 

Br 

1 

3.187 

Liquid. 

§3 

Iodine 

126.6 

I 

1 

4.948 

Solid. 

§i»  „ 

Fluorine 

19 

F 

1 

1.313 

Gas. 

o| 

Carbon 

12 

C 

4 

3.S-.6 

Solid. 

i  Jj 

Sulphur 

32 

S 

2,4 

2.05 

Solid. 

"S.2 

Phosphorous 

31 

p 

3,5 

1.83 

Solid. 

11 

Arsenic 

75 

As 

3,5 

5.73 

Solid. 

*       [_  Chromium 

52.4 

Cr 

4,6 

6.5 

Solid. 

Hydrogen 

1 

H 

1 

.069 

Gas. 

f  Manganese 

54 

Mn 

2,4,6 

8.03 

Solid. 

fee 

Boron 

11 

Bo 

3 

2.5? 

Solid. 

0 

Lead 

206.5 

Pb 

2,4 

11.37 

Solid. 

5 

Silver 

107.7 

Ag 

1 

10.53 

Solid. 

I 

Mercury 

200 

Hg 

1,2 

13.55 

Liquid. 

S3 

Magnesium 

24 

Mg 

2 

1.74 

Solid. 

X! 

to 

Tin 

117.7 

Sn 

2,4 

7.29 

Solid. 

1 

Copper 

63 

Cu 

1,2 

8.95 

Solid. 

1 

Iron 

56 

Fe 

2,4 

7.86 

Solid. 

I  1 

Aluminum 

27 

Al 

4 

2.6 

Solid. 

1 

Nickel 

58 

Ni 

2,4 

8.9 

Solid. 

o 

Cobalt 

59 

Co 

2,4 

S.5-.7 

Solid. 

a 

Zinc 

65 

Zn 

2 

7.15 

Solid. 

S 

Barium 

136.8 

Ba 

2 

3.75 

Solid. 

"S 

Strontium 

87.4 

Sr 

2 

2.54 

Solid. 

.2 

Calcium 

40 

Ca 

2 

1.57 

Solid. 

1 

"S 

Potassium 

39 

K 

1 

.87 

Solid. 

s 

Platinum 

194.4 

Pt 

4 

21.50 

Solid. 

^  Sodium 

23 

Na 

1 

.978 

Solid. 

158  APPENDIX. 


LIST   OF   CHEMICALS   AND  APPARATUS 
FOR   THE   COURSE. 


Preparation  of  Reagents. 

Aniline A  few  particles  in  H20  to  required  color. 

AgN03 1  g.  of  the  crystal  salt  to  40 cc  distilled 

H20. 

Alcohol Use  95  %. 

A12K2(S04)4  . .....1  g.  to!0cc. 

BaCl2 1  g.  to!0cc. 

Ba(N03)2 1  g.  to!0cc. 

Ca(OH)2   Digest  slaked  lime  in  H20,  and  filter. 

Co(]Sr03)2 1  g.  to  15 cc.     Use  the  crys.  salt. 

Chlorine  water  ....  Saturated  solution  of  chlorine  in  H20. 

Protect  from  light. 
Chloral  Hydrate  . .  .  1  g.  to  20 cc. 

Cr2K2(S04)4    Ig.  to!0cc. 

CuS04  Ig.  to!0cc. 

CoCl2 Ig.  to!0cc. 

C2H402 30%.  > 

CaCl2 1  g.  to!0cc. 

CaS04   Saturated  solution  in  H20. 

FeS04 Make  up  as  needed  with  distilled  H2O. 

Fe2Cl6 . 1  g.  to  10 cc.     Use  crys.  salt. 

HC1,  dil Beagent  strength  1  to  4  by  vol.     Equiv. 

to  8.5  %  HC1. 
HN03  dil 1  to  3  by  vol.     Equiv.  to  20  %  HN03. 


APPENDIX.  159 

H2S04,  dil 1  to  5  by  vol.  Equiv.  to  25  %  H2S04. 

Pour  the  acid  into  the  water  care- 
fully. 

HgCl2 Saturated  Solution. 

HgN03 1  g.  to20cc. 

H2S  Prepare  as  needed,  using  Kipp  gene- 
rator or  equiv.  with  FeS  and  com- 
mercial HC1  dil.  1  to  1  by  vol. 

H3As04 1  g.  to50cc. 

KMn04 Strong  sol.  1  g.  to  10 cc  ;  or,  better,  a  sat- 
urated solution. 

KMn04,  dil lcc  of  strong  sol.  to  200 cc  H20. 

KI 1  g.  to20cc. 

KOH Ig.  to!0cc. 

KCy 1  g.  to  10 c  c.  Use  cold  water.  Does  not 

keep  well. 

KBr Ig.  to20cc. 

K2O207 1  g.  to  10 cc.     Use  warm  H20. 

K4FeCyc 1  g.  to  15CC. 

KCyS 1  g.  to!5cc. 

K3FeCy6 Make  up  as  needed,  1  g.  to  15 c  c.  Does 

not  keep. 

K2Cr04   Ig.  to20cc. 

NaOH 1  g.  to  10 c  c.    Allow  to  settle,  and  decant. 

NH4OH Dilute  cone.  1  to  3  by  vol.  Equiv.  to 

10%  NH3. 

NH4C1 Ig.  to!0cc. 

Nad Ig.  to!0cc. 

(NH4)2C03 ........  200   g.    (NH4)2C03,    800 cc    H20,    and 

209CCNH4OH. 

(NH4)2S Saturate  KH4OH  with  H2S.  Add 

NH4OH  to  alkaline  reaction. 

(N"H4)2S2 Add  a  little  flowers  of  sulphur  to 

(NH4)2S. 


160  APPENDIX. 


.........  lg.  to20cc. 

MC12  ............  1  g.  to!0cc. 

Pb(C2H302)2  ......  lg.  to20cc. 

Starch  ...........  Digest  1  spoonful  in  300  c  c  cold  water, 

and  boil. 

SnCl2  ............  Dissolve  in  least  amount  of  hot  cone. 

H£l.  Dilute  with  H20,  lcc  to 
20  c  c  ,  and  keep  in  a  bottle  with  a 
piece  of  metallic  tin. 

SnCl4  ............  Dissolve  tin  in  aqua  regia.     Evaporate 

to  dryness.  Make  up  1  g.  to  20  cc 
or  more  dilute  if  desired. 

SrCl2   ............  1  g.  to!0cc. 

Sr(N03)2  .........  lg.  to!0cc. 

Touch  Paper,  made  by  dipping  filter  paper  in  strong  solution 
KN03  and  drying. 

ZnS04  ...........  Saturated  solution. 

ZnCl2  ............  1  g-  to  10CC. 


APPENDIX. 


161 


PURCHASING   LIST. 


Alcohol  .         .         .        ". 
Ammonium  Carbonate 
Ammonium  Hydrate,  cone. 

AS203      .    •  .     .   ;•  . 


Borax          . 

Carbon  Disulphide         .      '  . 

Copper  clippings 

CuS04  .         .         .        . 

CaCl2         '.        .  :     . 

CaO        ...~      ... 

CaF2  .'.       .  •'••}.        .        , 

Cotton,  common 

Cotton,  gun 

Charcoal,  powdered        »-     ;  . 

Charcoal,  sticks  for  blowpipe 

Coal,  bituminous    .         . 

Ether  .... 

FeS04     ..... 

FeS,  fused  .... 

HgO       .         .      '  .         .         . 

Hydrochloric  Acid,  C.P.  Sp.  G. 

Hydrochloric  Acid,  com.  Sp.  G. 

Iodine,  sublimed 

Iron  Filings,  very  fine    . 

KNO,.         .         ... 

KBr        .         .      ;  .         .         . 

KI       .  \". 

KC!03 


1.20 
1.20 


Fou  20  PUPILS. 
1  quart, 
i  pound. 
4  pounds. 
1  ounce. 
£  pound, 
i  pound. 
1  pound. 
1  pound. 
^  pound. 
I  pound. 

1  pound. 

2  ounces. 
1  ounce. 
\  ounce. 
1  pound. 
20. 

^  pound. 
1  pound. 
^  pound. 

1  pound. 
£  pound. 
6  pounds. 

2  pounds. 
£  ounce. 

J  pound. 
£  pound. 
2  ounces. 
2  ounces. 
2  pounds. 


162 


APPENDIX. 


K4FeCy6 

Lead,  metallic     ...... 

Litmus  Paper,  red  and  blue 

Mercury,  metallic        ..... 

Mn02 

Magnesium  Ribbon    ..... 
Marble,  White        .         .         .  .        ; 

Nad        ;   ."      ,        ..'•      .         .         .         .'- 
NH41TO3,  anhydrous       .         .         .         .'• 

NH4C1.        .    ' 

NaC2H302      . 

Na2C03       .         .       - .        .         .     ?.  .   -     . 
NaOH    .         .         .       ...  .'     .         . 

Nitric  Acid,  Sp.  G.  1.42      .         .         . 
Plaster  of  Paris     .  .         . 

Pb(NO,)a    .        .        .       V       .        .       ;'. 
PbS,  powdered       .         .         .         .         .         . 

Pbo  .    ;-.      .      .      . 

Phosphorus    .         .         .         .         . 

Potassium,  metallic 

Potassium  Hydroxide,  sticks 
Platinum  Wire,  for  blowpiping  . 
Platinum  Foil         .         .         .        -t  '•      .      .   . 
Starch         .         .         .         .         .         . 

Sr(X03)2 

Sodium,  metallic 

Sulphur,  roll  .         •         .         . 

Sulphur,  flowers  .         . 

Sulphuric  Acid,  Sp.  G.  1.84    . 

Sugar,  granulated 

Zinc,  sheet 

Zinc,  granulated,  made   by  pouring   melted 

lumps  into  H20 

ZnS,  powdered  . 


^  pound, 
i  pound. 
1  'sheet  each. 

1  pound. 
£  pound. 
^  ounce. 

2  pounds. 

1  pound. 

2  pounds. 

1  pound. 

2  ounces. 
1  pound. 
£  pound. 

3  pounds. 

1  pound. 

2  ounces. 
1  ounce. 
1  ounce. 
1  ounce, 
i  ounce. 
1  pound. 
5  grams. 
5  grams. 
L  pound. 
%  pound. 
£  ounce. 
J  pound. 
1  pound. 
9  pounds. 
1  pound. 

1  pound. 

2  pounds. 
1  ounce. 


Order  Chemicals  not  otherwise  specified  in  1  ounce  packages.    Use 
C.  P.  Chemicals  and  distilled  water  for  solutions  wherever  possible. 


APPENDIX.  163 


Apparatus  required  for  each  Pupil. 

1  Metric  and  English  rule.  —  1  foot. 
6  Test-tubes,  g-"x6". 
1  Rubber  delivery  tube. 
1  Glass  delivery  tube. 
1  Piece  of  window  glass  2"  square. 
1  Piece  of  blue  glass  2"  square. 
1  Evaporating  dish. 
1  Pair  nippers. 
1  Watch  crystal,  diameter  2", 
1  Small  microscope. 
10  Filters,  5". 
1  Funnel,  2f . 
1  Glass  rod. 
1  Small  magnet. 
1  Tin-box  cover. 

1  Pneumatic  trough. 

4  Wide-mouth  4  oz.  bottles. 
Wide-mouth  1  oz.  bottle. 
Narrow-mouth  4  oz.  bottle. 
Foot  No.  18  iron  wire. 
Foot  fine  iron  wire. 
Combustion  spoon. 

2  Pieces  white  cardboard,  2"  square. 

4  Pieces  glass  tubing,  4"  diameter,  ?>"  long. 

1  Glass  tumbler. 

1  Paraffin  candle. 

1  Lamp  chimney,  Argand. 

1  Strip  zinc,  4"xl". 

1  Blowpipe. 

1  Piece  of  wire  gauze,  4"  square,  iron. 

1  Tripod  or  ring  stand. 

1  Test-tube  holder. 

1  Wash  bottle. 

Assorted  rubber  stoppers  and  corks  to  fit  bottles  and  test  tubes. 


YB  36031 


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